Make xf86CompatOutput() return NULL when there are no privates
Some drivers (mach64 w/o DRI for instance) don't initialize privates. Signed-off-by: Matthieu Herrb <matthieu.herrb@laas.fr>
Some drivers (mach64 w/o DRI for instance) don't initialize privates. Signed-off-by: Matthieu Herrb <matthieu.herrb@laas.fr>