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 basically reverts commit 54735dec, which tried to avoid the
GLib-defined types in favor the standard C ones. One exception to this
is the bool type, for which the commit introduces a new type CoglBool.
Let's just get rid of this type in favor of having consistency with the
GLib types. Note by the way that neither CoglBool nor gboolean (which
has a size of `int`) are completely compatible with bool (size `char`).
https://gitlab.gnome.org/GNOME/mutter/merge_requests/321
