cogl_object_[get|set]_value_object() are annotated as [get|set]-value-func
for objects and primitives, so they must be visible for any derived types
to be usable from introspection.
https://gitlab.gnome.org/GNOME/mutter/-/issues/1146
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