zink: always force flushes when originating from api frontend
What does this MR do and why?
zink: always force flushes when originating from api frontend
flags=0 is used for e.g., glFenceSync, which apps use to insert sync points
to determine when all prior work has completed. eliding these flushes into no-ops
is fine for all scenarios except when the last op was a present, in which
case the no-op (previous) fence will not sync as expected for the present and
graphical artifacts will result
in the future, this may be changed back to the previous behavior if/when presentation
gains timeline semaphore capabilities by providing the last timeline id
as a fence instead of the last batch
fixes #10386