virgl: reemit resources on first draw/clear/compute

virgl: reemit resources on first draw/clear/compute

This gives us more precise resource tracking.  It can be beneficial
because glFlush is often followed by state changes.  We don't want
to reemit resources that are going to be unbound.

Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>