The RandR CRTC structures are freed when their resource IDs are
destroyed during server shut down, which is before the screen is
closed. Calling back into RandR with stale pointers just segfaults the
server.
Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Tested-by: Knut Petersen <knut_petersen@t-online.de>