sync glapi with mesa

[George Sapountzis]

Hi,

I put 4 patches at http://people.freedesktop.org/~gsap7/glapi/ that
sync xorg HEAD with glapi from mesa HEAD.

I know that the xorg development process has changed and xorg head may
not track mesa head. So, if you tell me when it's appropriate to sync
glapi, I'll forward-port and re-submit. Having said that, the patches
have received limited testing with xephyr, so please review and test.

regards,
George.