gio: Add missing (type filename) annotations
gio: Add missing (type filename) annotations

These differentiate between strings in the GLib filename encoding, and
strings in UTF-8.

https://bugzilla.gnome.org/show_bug.cgi?id=700756

endlessm/glib,johne53/MB3Glib,endlessm/glib,endlessm/glib,endlessm/glib,johne53/MB3Glib,johne53/MB3Glib,johne53/MB3Glib,endlessm/glib,johne53/MB3Glib,johne53/MB3Glib