[Mesa-dev] Initial support for EXT_external_objects v5

[Timothy Arceri]

V5 addresses all Samuel's comments from v4 which was a bunch of minor comments
and updated to the gallium trace tool.

There have been a few calls for piglit tests to be written so I'll hold off on
pushing for now unless the AMD guys are happy for this to land. Curently it's
just been tested with SteamVR.

I'll probably just push the UUID patches for now once I get an
updated rb on patch 17.

Thanks,
Tim

Series available at:
    https://github.com/tarceri/Mesa.git (memobj3)