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
As previously commented in the code, SGI_video_sync is per-display, rather
than per-renderer. The is_direct flag for the renderer was tested before
it was initialized (per-display) and that resulted in SGI_video_sync
never being used.
https://bugzilla.gnome.org/show_bug.cgi?id=779039
