Move xwayland test to the new harness.
This is the only test that can actually skip. It does it by exit(77) and that
is fine, because there is only one test case in the file so far. To get rid of
the exit() calls we need to return a value from the TEST() function but that is
a big surgery for another time.
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>