[PATCH] glproto: Sync glcore.h with mesa HEAD.

[Luc Verhaegen]

It was, i guess, supposed to be the same file when modularization 
happened, but sadly it didn't pan out like that:
* EXT_texture_from_pixmap was added close to 4ys ago.
* other bits have been written out of mesa and the xserver (another
  patch will follow to clean up some cruft that required those other
  bits)
* not sure what we need sys/types for in this header, but i chose to
  use the mesa version as to keep both in 100% sync.

Luc Verhaegen.