ClutterContent has the ability to dictate the layout of any
given actor, through the CLUTTER_REQUEST_CONTENT_SIZE request
mode.
However, there is no way for ClutterContent implementations
to notify their attached actors that the content size changed.
Add a new optional ClutterContent.invalidate_size() vfunc and
clutter_content_invalidate_size().
https://gitlab.gnome.org/GNOME/mutter/merge_requests/405
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