include: Sync Khronos headers for OpenGL 4.6

Taken from c21e602b9fda1d3bbaecb08194592f67e6a0649b from
OpenGL-Registry.

Signed-off-by: Adam Jackson <ajax@redhat.com>
Acked-by: Ilia Mirkin <imirkin@alum.mit.edu>
5 files changed