Patches applied as cb948aef0caae7e9f3b61c57aa06a73be04a5868 and
following with a few minor fixes.

For cl-gtk4, I used the patch propagating gtk instead of the patch
copying files from several gtk-related libraries (it will probably be
easier to maintain). If one day we have a package with a standalone
binary depending on cl-gtk4, we will just have not to forget to wrap it
so that it can find GI_TYPELIB_PATH (e.g. like for gnome-music, sushi,
gnome-characters, etc).

Thanks.