For compute shaders stats avail was never signalling because nothing
flushed.
Fixes dEQP-VK.query_pool.statistics_query.host_query_reset.compute_shader_invocations.64bits_cmdcopyquerypoolresults_primary
and others
Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11913>