In the Linux case, it simply doesn’t pass -g to the compiler when OPTIMIZE=4, which achieves the same effect. (See the definition for CFLAGS_OPT1/2/3/4 in dtool/Config.pp).
I suspect the OSX ppremake scripts may not be set up to do the equivalent thing properly. Is there a compiler option on OSX, similar to -g, to avoid putting the symbols there in the first place? You can experiment with customizing your CFLAGS variable to see if you get this effect.
David