This lets us verify that all callers are actually testing for a
successful hash lookup at compile time.
All current users of hash_table_lookup are converted to the new
wm_lookup_window() and the appropriate success check is added.
This fixes any call sites that used to assume a successful return
and dereference a NULL pointer.
This closes http://bugs.freedesktop.org/show_bug.cgi?id=83994
The xwayland test has been failing because weston crashes due to
a hash lookup failure and a subsequent dereference of the returned
NULL pointer.
Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>