Fog is explicitly deprecated in favour of CoglSnippet API,
and in nowhere we are using this deprecated feature, which
means we can simply drop it without any sort of replacement.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/458
This is for all intents and purposes the same as
`cogl_object_ref/unref`, but still refers to handles rather than
objects (while we're trying to get rid of the former) so it's a bit of
unnecessary redundant API.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/451