When switching to "UNIX-style paths" as needed for the new includes,
including <GL/gl.h> and <GL/glu.h> doesn't work anymore on Mac OS...
The two headers are really located in the OpenGL SDK 1.2 CFM like this:
OpenGL:Headers:gl.h
OpenGL:Headers:glu.h
There are also some compat copies, that *used* to work with Mac paths:
OpenGL:Headers:GL/gl.h
OpenGL:Headers:GL/glu.h
The easiest fix is to make SDL_opengl.h include the proper header names,
by adding a special case for the MACOS platform in addition to the MACOSX