http://bugs.winehq.org/show_bug.cgi?id=15375
--- Comment #1 from Roderick Colenbrander thunderbird2k@gmx.net 2008-09-22 13:58:53 --- No idea why that is needed perhaps something went wrong during configure (check if it found the correct libGL path and not another libGL). It must have found a lib as else wine would have been build without opengl in the first place.
GLX_SGIX_fbconfig is required for wine's opengl support. I'm not sure if xquartz offers it but you could try to let the check pass in dlls/winex11.drv/opengl.c as some drivers don't advertise support for it properly.