The issue is that it’s getting confused whether or not it’s building for 32-bits or 64-bits, which isn’t always obvious on OSX.
1.7.2 does not support (nor does 1.8.0, for that sake) 64-bits OSX, so if you compile it, you must do it in 32-bits mode. Panda3D is compiled against the version of Python that you run makepanda with, so make sure that you’re running Python in 32-bits mode. (Only works with the version of Python that is shipped with OS X by default.) Be sure to “rm -rf built” to make a clean build before retrying.