clutter/stage-cogl: Protect against extremely high refresh rates

After 4faeb127, the maximum time allowed for an update to happen
is calculated as:

  max_render_time_allowed = refresh_interval - 1000 * sync_delay;

However, extremely small refresh intervals -- that come as consequence
to extremely high refresh rates -- may fall into an odd numerical range
when refresh_interval < 1000 * sync_delay. That would give us a negative
time.

To be extra cautious about it, add another sanity check for this case.

Change suggested by Jasper St. Pierre.

GNOME/mutter!363
4 jobs for !363 with always-presentation in 17 minutes and 43 seconds (queued for 2 seconds)
detached
Status Job ID Name Coverage
  Review
passed #320710
check-commit-log

00:00:37

 
  Build
passed #320711
build-mutter

00:12:13

 
  Test
passed #320713
can-build-gnome-shell

00:02:41

passed #320712
test-mutter

00:04:53