This has no real effect on SDL since we run with the `dummy` driver that
just does everything offscreen. However, Chocolate Doom by default
pauses for a second on startup if running fullscreen, so that the
display has time to settle if the monitor changes modes. Since statcheck
runs through hundreds of fairly short demos, this equates to a useless
pause that makes the whole run take much longer.
This allows the testrunner script to be eliminated, and on one of my
lower-spec machines this makes a significant difference because Python
startup can be slow, and it's now not necessary to invoke it for every
run.
