Detect if a drawable has been moved from an original crtc to a new crtc
with a lower current vblank count than the original crtc inbetween
glXSwapBuffers() calls. Reinitialize drawable's last_swap_target
before scheduling next swap if such a move has taken place.
last_swap_target defines the baseline for scheduling the next swap.
If a movement between crtc's is not taken into account, the swap may
schedule for a vblank count on the new crtc far in the future, resulting
in a apparent "hang" of the drawable for a long time.
Fixes Bugzilla bug #28383.
Signed-off-by: Mario Kleiner <mario.kleiner@tuebingen.mpg.de>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Keith Packard <keithp@keithp.com>