POSIX ERE, while pretty standard is also very old and severely limited.
In fact, it's so limited that Intel CI's own test blacklist,
tests/intel-ci/blacklist.txt, doesn't even work with it due to the lack
of support for backreferences.

Since we're already using glib in other parts of igt, let's just start
using glib's regular expression matching instead of the POSIX regex API.
This gives us full perl compatible regular expressions and in turn, also
gives us python compatible regular expressions to match piglit.

Reviewed-by: Petri Latvala <petri.latvala@intel.com>
Signed-off-by: Lyude Paul <lyude@redhat.com>