I built latest server and copied over a mesa 7.8 dri2 driver to use with it,
and it crashed in here starting compiz. Looks like we need to validate the
flush extension is registered before calling invalidate.
Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Michel Dänzer <michel@daenzer.net>
Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Keith Packard <keithp@keithp.com>