glapi/glx: Thunk non-ABI calls through GetProcAddress
glapi/glx: Thunk non-ABI calls through GetProcAddress

Reviewed-by: Ian Romanick <2b237cafb16dc45038e85df6c85e74e6d899eba9@intel.com>
Signed-off-by: Adam Jackson <4482611cc290c2ce1399431891dcb9221c95f994@redhat.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler