Add the GLIB_AVAILABLE_IN_ALL annotation to all old functions (that
haven't already been annotated with the GLIB_AVAILABLE_IN_* macros or a
deprecation macro).
If we discover in the future that we cannot use only one macro on
Windows, it will be an easy sed patch to fix that.
https://bugzilla.gnome.org/show_bug.cgi?id=688681
add GSimplePermission, a trivial const implementation of GPermission
can-request and can-release are always false for this implementation and
the value of 'allowed' is decided at construction.