Commenting that typedef out leads to the world ending:
c:\panda3d-1.7.0\panda\src\gles2gsg\gles2gsg.h(69) : warning C4005: 'APIENTRY' : macro redefinition
C:\Program Files\Microsoft SDKs\Windows\v7.1\Include\windef.h(126) : see previous definition of 'APIENTRY'
config_gles2gsg.cxx(21) : warning C4273: 'gles2gsg_cat' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\gles2gsg\config_gles2gsg.h(23) : see previous definition of 'gles2gsg_cat'
config_gles2gsg.cxx(21) : warning C4273: 'NotifyCategoryGetCategory_gles2gsg::NotifyCategoryGetCategory_gles2gsg' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\gles2gsg\config_gles2gsg.h(23) : see previous definition of '{ctor}'
config_gles2gsg.cxx(21) : warning C4273: 'NotifyCategoryGetCategory_gles2gsg::get_category' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\gles2gsg\config_gles2gsg.h(23) : see previous definition of 'get_category'
config_gles2gsg.cxx(36) : warning C4273: 'init_libgles2gsg' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\gles2gsg\config_gles2gsg.h(25) : see previous definition of 'init_libgles2gsg'
cl /Fo"Opt3-Cygwin\gles2gsg_gles2gsg.obj" /nologo /c /I"." /I"C:\panda3d-1.7.0\panda" /I"..\cull" /I"..\display" /I"..\downloader" /I"..\effects" /I"..\event" /I"..\express" /I"..\glstuff" /I"..\gobj" /I"..\
gles2gsg.cxx
c:\panda3d-1.7.0\panda\src\gles2gsg\gles2gsg.h(69) : warning C4005: 'APIENTRY' : macro redefinition
C:\Program Files\Microsoft SDKs\Windows\v7.1\Include\windef.h(126) : see previous definition of 'APIENTRY'
c:\panda3d-1.7.0\panda\src\glstuff\glmisc_src.cxx(161) : warning C4273: 'GLES2init_classes' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glmisc_src.h(45) : see previous definition of 'GLES2init_classes'
c:\panda3d-1.7.0\panda\src\glstuff\glTextureContext_src.cxx(17) : warning C4273: '_type_handle' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glTextureContext_src.h(58) : see previous definition of 'private: static TypeHandle GLES2TextureContext::_type_handle'
c:\panda3d-1.7.0\panda\src\glstuff\glTextureContext_src.cxx(17) : error C2491: 'GLES2TextureContext::_type_handle' : definition of dllimport static data member not allowed
c:\panda3d-1.7.0\panda\src\glstuff\glTextureContext_src.cxx(36) : warning C4273: 'GLES2TextureContext::evict_lru' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glTextureContext_src.h(28) : see previous definition of 'evict_lru'
c:\panda3d-1.7.0\panda\src\glstuff\glVertexBufferContext_src.cxx(15) : warning C4273: '_type_handle' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glVertexBufferContext_src.h(55) : see previous definition of 'private: static TypeHandle GLES2VertexBufferContext::_type_handle'
c:\panda3d-1.7.0\panda\src\glstuff\glVertexBufferContext_src.cxx(15) : error C2491: 'GLES2VertexBufferContext::_type_handle' : definition of dllimport static data member not allowed
c:\panda3d-1.7.0\panda\src\glstuff\glVertexBufferContext_src.cxx(33) : warning C4273: 'GLES2VertexBufferContext::evict_lru' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glVertexBufferContext_src.h(33) : see previous definition of 'evict_lru'
c:\panda3d-1.7.0\panda\src\glstuff\glIndexBufferContext_src.cxx(15) : warning C4273: '_type_handle' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glIndexBufferContext_src.h(53) : see previous definition of 'private: static TypeHandle GLES2IndexBufferContext::_type_handle'
c:\panda3d-1.7.0\panda\src\glstuff\glIndexBufferContext_src.cxx(15) : error C2491: 'GLES2IndexBufferContext::_type_handle' : definition of dllimport static data member not allowed
c:\panda3d-1.7.0\panda\src\glstuff\glIndexBufferContext_src.cxx(33) : warning C4273: 'GLES2IndexBufferContext::evict_lru' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glIndexBufferContext_src.h(31) : see previous definition of 'evict_lru'
c:\panda3d-1.7.0\panda\src\glstuff\glGeomContext_src.cxx(15) : warning C4273: '_type_handle' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glGeomContext_src.h(74) : see previous definition of 'private: static TypeHandle GLES2GeomContext::_type_handle'
c:\panda3d-1.7.0\panda\src\glstuff\glGeomContext_src.cxx(15) : error C2491: 'GLES2GeomContext::_type_handle' : definition of dllimport static data member not allowed
c:\panda3d-1.7.0\panda\src\glstuff\glGeomContext_src.cxx(23) : warning C4273: 'GLES2GeomContext::~GLES2GeomContext' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glGeomContext_src.h(32) : see previous definition of '{dtor}'
c:\panda3d-1.7.0\panda\src\glstuff\glGeomContext_src.cxx(39) : warning C4273: 'GLES2GeomContext::get_display_list' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glGeomContext_src.h(35) : see previous definition of 'get_display_list'
c:\panda3d-1.7.0\panda\src\glstuff\glGeomContext_src.cxx(70) : warning C4273: 'GLES2GeomContext::release_display_lists' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glGeomContext_src.h(37) : see previous definition of 'release_display_lists'
c:\panda3d-1.7.0\panda\src\glstuff\glGeomContext_src.cxx(105) : warning C4273: 'GLES2GeomContext::remove_munger' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glGeomContext_src.h(39) : see previous definition of 'remove_munger'
c:\panda3d-1.7.0\panda\src\glstuff\glGeomMunger_src.cxx(17) : warning C4273: '_type_handle' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glGeomMunger_src.h(76) : see previous definition of 'private: static TypeHandle GLES2GeomMunger::_type_handle'
c:\panda3d-1.7.0\panda\src\glstuff\glGeomMunger_src.cxx(17) : error C2491: 'GLES2GeomMunger::_type_handle' : definition of dllimport static data member not allowed
c:\panda3d-1.7.0\panda\src\glstuff\glGeomMunger_src.cxx(19) : warning C4273: '_deleted_chain' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glGeomMunger_src.h(36) : see previous definition of 'public: static DeletedChain<GLES2GeomMunger> GLES2GeomMunger::_deleted_chain'
c:\panda3d-1.7.0\panda\src\glstuff\glGeomMunger_src.cxx(19) : error C2491: 'GLES2GeomMunger::_deleted_chain' : definition of dllimport static data member not allowed
c:\panda3d-1.7.0\panda\src\glstuff\glGeomMunger_src.cxx(27) : warning C4273: 'GLES2GeomMunger::GLES2GeomMunger' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glGeomMunger_src.h(34) : see previous definition of '{ctor}'
c:\panda3d-1.7.0\panda\src\glstuff\glGeomMunger_src.cxx(52) : warning C4273: 'GLES2GeomMunger::~GLES2GeomMunger' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glGeomMunger_src.h(35) : see previous definition of '{dtor}'
c:\panda3d-1.7.0\panda\src\glstuff\glGeomMunger_src.cxx(71) : warning C4273: 'GLES2GeomMunger::wp_callback' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glGeomMunger_src.h(38) : see previous definition of 'wp_callback'
c:\panda3d-1.7.0\panda\src\glstuff\glGeomMunger_src.cxx(83) : warning C4273: 'GLES2GeomMunger::munge_format_impl' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glGeomMunger_src.h(41) : see previous definition of 'munge_format_impl'
c:\panda3d-1.7.0\panda\src\glstuff\glGeomMunger_src.cxx(225) : warning C4273: 'GLES2GeomMunger::premunge_format_impl' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glGeomMunger_src.h(43) : see previous definition of 'premunge_format_impl'
c:\panda3d-1.7.0\panda\src\glstuff\glGeomMunger_src.cxx(354) : warning C4273: 'GLES2GeomMunger::compare_to_impl' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glGeomMunger_src.h(45) : see previous definition of 'compare_to_impl'
c:\panda3d-1.7.0\panda\src\glstuff\glGeomMunger_src.cxx(378) : warning C4273: 'GLES2GeomMunger::geom_compare_to_impl' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glGeomMunger_src.h(46) : see previous definition of 'geom_compare_to_impl'
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.cxx(24) : warning C4273: '_type_handle' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.h(95) : see previous definition of 'private: static TypeHandle GLES2ShaderContext::_type_handle'
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.cxx(24) : error C2491: 'GLES2ShaderContext::_type_handle' : definition of dllimport static data member not allowed
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.cxx(54) : warning C4273: 'GLES2ShaderContext::GLES2ShaderContext' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.h(35) : see previous definition of '{ctor}'
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.cxx(358) : warning C4273: 'GLES2ShaderContext::~GLES2ShaderContext' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.h(36) : see previous definition of '{dtor}'
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.cxx(369) : warning C4273: 'GLES2ShaderContext::release_resources' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.h(78) : see previous definition of 'release_resources'
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.cxx(424) : warning C4273: 'GLES2ShaderContext::bind' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.h(40) : see previous definition of 'bind'
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.cxx(466) : warning C4273: 'GLES2ShaderContext::unbind' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.h(41) : see previous definition of 'unbind'
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.cxx(507) : warning C4273: 'GLES2ShaderContext::issue_parameters' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.h(42) : see previous definition of 'issue_parameters'
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.cxx(576) : warning C4273: 'GLES2ShaderContext::disable_shader_vertex_arrays' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.h(43) : see previous definition of 'disable_shader_vertex_arrays'
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.cxx(614) : warning C4273: 'GLES2ShaderContext::update_shader_vertex_arrays' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.h(44) : see previous definition of 'update_shader_vertex_arrays'
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.cxx(704) : warning C4273: 'GLES2ShaderContext::disable_shader_texture_bindings' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.h(46) : see previous definition of 'disable_shader_texture_bindings'
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.cxx(765) : warning C4273: 'GLES2ShaderContext::update_shader_texture_bindings' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.h(47) : see previous definition of 'update_shader_texture_bindings'
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.cxx(865) : warning C4273: 'GLES2ShaderContext::glsl_report_shader_errors' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.h(73) : see previous definition of 'glsl_report_shader_errors'
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.cxx(888) : warning C4273: 'GLES2ShaderContext::glsl_report_program_errors' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.h(74) : see previous definition of 'glsl_report_program_errors'
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.cxx(911) : warning C4273: 'GLES2ShaderContext::glsl_compile_entry_point' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.h(75) : see previous definition of 'glsl_compile_entry_point'
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.cxx(949) : warning C4273: 'GLES2ShaderContext::glsl_compile_shader' : inconsistent dll linkage
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.h(76) : see previous definition of 'glsl_compile_shader'
c:\panda3d-1.7.0\panda\src\glstuff\glShaderContext_src.cxx(971) : error C2039: '_glProgramParameteri' : is not a member of 'GLES2GraphicsStateGuardian'