codegen: Pass member to SubMarshallingSource rather than name
codegen: Pass member to SubMarshallingSource rather than name

This way we can check attributes on the member.

dezelin/spice,virtualAMP/spiceplay,alon/spice-server,fgouget/spice,mathslinux/spice,Fantu/spice,SPICE/spice,alon/spice-server,ya-mouse/spice,mathslinux/spice,elmarco/spice,freedesktop-unofficial-mirror/spice__spice,virtualAMP/spiceplay,alon/spice-server,virtualAMP/spiceplay,dezelin/spice,Fantu/spice,dezelin/spice,elmarco/spice,mathslinux/spice,fgouget/spice,elmarco/spice,ya-mouse/spice,ya-mouse/spice,SPICE/spice,alon/spice-server,Fantu/spice,SPICE/spice,alon/spice-server,freedesktop-unofficial-mirror/spice__spice,dezelin/spice,dezelin/spice,virtualAMP/spiceplay,Fantu/spice,mathslinux/spice,elmarco/spice,elmarco/spice,freedesktop-unofficial-mirror/spice__spice,freedesktop-unofficial-mirror/spice__spice,fgouget/spice,fgouget/spice,freedesktop-unofficial-mirror/spice__spice,mathslinux/spice