if the libgpu940.a is compiled with C, and you use C++ to compile your own program you have to let the compiler know that the functions of libgpu940 are compiled with C.
When you include <GL/gl.h> and <GL/gl_float.h> do it like this:
Arggh.. Can someone please give me step by step instructions about how to sucessfully set this up with devkitGP2X? >_> I just can't seem to get it right and I'm itching to get some nice GL code running.
I just want to get the gpugears to work for now O_O