i965/drm: Switch from uthash to Mesa's hash table.

i965/drm: Switch from uthash to Mesa's hash table.

No performance data has been gathered about this choice.  I just don't
want that many hash tables.  Chris points out that this is not
performance critical - we should not be recreating that many handles
from scratch.  In the past we used a linear list, which became
unreasonable in stress tests that used hundreds of thousands of BOs.
In real usage, it shouldn't matter that much.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Jason Ekstrand <jason@jlekstrand.net>