If a test is not expected to succeed, then running it could be considered
to be a waste of resources, particularly if the failure might manifest
as an indefinite hang (see cogl!11), or if the test is likely to dump core
and trigger "expensive" crash-reporting mechanisms like systemd-coredump,
corekeeper, abrt or apport.
Skip the tests that are expected to fail. They can still be requested via
an environment variable, which can be set after fixing a bug to check which
tests are now passing.
Originally cogl!15, adapted for mutter's fork of cogl to use gboolean
instead of CoglBool.
https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1272
Signed-off-by: Simon McVittie <smcv@debian.org>