sys: fix up c_type when the actual type is more specific
sys: fix up c_type when the actual type is more specific

gtk-rs/gir,EPashkin/gir,GuillaumeGomez/gir,gtk-rs/gir,EPashkin/gir,insanebits/gir,GuillaumeGomez/gir,gkoz/gir,GuillaumeGomez/gir,gkoz/gir,insanebits/gir,gtk-rs/gir