Add missing G_GNUC_INTERNAL
Add missing G_GNUC_INTERNAL

Trivial fix

guodong/spice-gtk,SPICE/spice-gtk,Fantu/spice-gtk,guodong/spice-gtk,flexVDI/spice-gtk,elmarco/spice-gtk,freedesktop-unofficial-mirror/spice__spice-gtk,guodong/spice-gtk,fgouget/spice-gtk,freedesktop-unofficial-mirror/spice__spice-gtk,Fantu/spice-gtk,SPICE/spice-gtk,freedesktop-unofficial-mirror/spice__spice-gtk,elmarco/spice-gtk,flexVDI/spice-gtk,elmarco/spice-gtk,freedesktop-unofficial-mirror/spice__spice-gtk,elmarco/spice-gtk,Fantu/spice-gtk,fgouget/spice-gtk,SPICE/spice-gtk,fgouget/spice-gtk,guodong/spice-gtk,SPICE/spice-gtk,Fantu/spice-gtk