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
This macro was introduced so as to be able to be built without GLib.
However, this feature was long ago removed, and in Mutter we depend on
it anyway, so let's get rid of it in favor of more consistency.
