[Mesa-dev] Subset of patches from wip-high-priority that can be useful v2

[Andres Rodriguez]

Following are a subset of patches from my wip-high-priority branch that
may be useful outside that context.

The HW priority debugging may take a little while, so I wanted to make some
of the more generic bits to be available on master as other work could benefit
from it.

v2: Fixed a rebasing mistake, indentation and commit message logs