The tr1 shared_ptr shim names its shared null counter null_counter, so
it survives MacTypes.h defining nil as an object-like macro. That
header arrives through apple_compat.h on every Apple build.
gl_texture2d.inl uses the unsuffixed GL 3.0 names GL_RGB9_E5 and
GL_R11F_G11F_B10F, with fallbacks to the EXT spellings or the literal
values when a header supplies neither. Apple keeps the EXT names in the
legacy <OpenGL/glext.h>, which the gl3.h path this tree takes never
pulls in.