glapi: Import gl.xml from Khronox registry

Import revision 26792 on 2014-05-22 from
(https://cvs.khronos.org/svn/repos/ogl/trunk/doc/registry/public/api/gl.xml).

I want to generate piglit-dispatch code from the official Khronos XML
rather than scraping GL headers and deprecated *.spec files.

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
glapi: Fix bugs in Khronos' gl.xml

Fix the category of the bitmask enums to glOcclusionQueryEventMaskAMD.

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
WIP dispatch: Generate from Khronos XML

TODO: Test for regressions
TODO: Commit message
Signed-off-by: Chad Versace <chad.versace@linux.intel.com>