If we present several pixmaps in advance for different msc, the later one
shouldn't cancel the previous ones.
This reverts a change made by commit
e6f5d9d7b7
Without this fix, vblank_mode=0 glxgears doesn't update
with the present fallback.
Signed-off-by: Axel Davy <axel.davy@ens.fr>
Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Keith Packard <keithp@keithp.com>