Reapply "gallium/u_threaded: buffer sharedness tracking"
What does this MR do and why?
Reapply "gallium/u_threaded: buffer sharedness tracking"
This reverts commit 96cf4531e11eac8175671be990a02c7b5d17fb60.
At some point we need to think about bringing this back. Now seems like a good time to begin the discussion. cc @pepp @mareko since your driver was adversely affected