Group all the three config files from clutter/cogl/meta into one
and also remove unnused configurations and replace duplicated ones
This also fixes Cogl usage of HAS_X11/HAS_XLIB to match the expected
build options
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3368>
ClutterActor took a reference in its transition 'stopped' handler,
aiming to keep the transition alive during signal emission even if it
was removed during. This is, however, already taken care of by
ClutterTimeline, by always taking a reference during its 'stopped'
signal emission, so no need to add another one.
This also has the bonus of making reference ownership simpler, as well
as avoidance of double free if an actor was destroyed before a
transition has finished.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/828
In cogl use cogl-config.h and in clutter use clutter-build-config.h. We
can't use clutter-config.h in clutter because its already used and
installed.
https://bugzilla.gnome.org/show_bug.cgi?id=768976
