This diff seems larger than it is since upstream reindented some
sources. This updates libdrm_intel to -current (which only affect the
GEM code) and libdrm to 2.4.15. bumping both minor versions.
Discussed with matthieu@
This is needed for us to be able to update Mesa and xf86-video-intel.
Includes a few fixes, as well as the intel bufmgr interface and the
modesetting interface (which currently errors when you check if it's
enabled).
ok matthieu@