Nah. It works perfectly, without a single warning, once
#define GL_GLEXT_PROTOTYPES
is added, but Raphaël didn't want that due to problems with broken nVIDEA drivers or somthing like that.
(...)
This is not a Linux versus FreeBSD issue.
Well, the Linux ABI tells this :
" 4.4. glx.h must include the prototype of the glXGetProcAddressARB extension described above.
4.5. All OpenGL 1.2 and ARB_multitexture, GLU 1.3, and GLX 1.3 entry points and enumerants must be present in the corresponding header files gl.h, glu.h, and glx.h, even if only OpenGL 1.1 is implemented at runtime by the associated runtime libraries. "
So if your system was compliant, you should have all the glMulti* prototypes defined in your gl.h file and glXGetProcAddressARB too.... So you should not have any warning.
Nothing is mentionned in the ABI about any need for 'GL_GLEXT_PROTOTYPES' protection of these calls, so well, I still think that it's somehow a problem in your headers :-)
Lionel