Drop GLcore dependency from glx module.
Work around double destroy case and add DRIUnlockedCallback() function.
New files, lots of code coming from GL/mesa/X/xf86glx.c and the libGL
loader code.
Olli Helenius)
- Fix some distcheck problems for non-solaris systems
- Change server version number from the Xorg rev to an independent one
- _POSIX_SOURCE and _XOPEN_SOURCE defined to the right values