In theory this wait is required for correct behaviour of discarded threads with
ATEST. Mesa usually waits before the instruction after ATEST, so this wait will
get optimized out by va_merge_flow, but as our scheduler gets more sophisticated
this could become an issue.
Let's stay on the safe side and insert the recommended wait.
No shader-db changes.
Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Cc: mesa-stable
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17428>