marshaller: Make get_nw_offset() handle deep member references
marshaller: Make get_nw_offset() handle deep member references

Fantu/spice-common,elmarco/spice-common,freedesktop-unofficial-mirror/spice__spice-common,SPICE/spice-common,SPICE/spice-common,fgouget/spice-common,Fantu/spice-common,freedesktop-unofficial-mirror/spice__spice-common,fgouget/spice-common,freedesktop-unofficial-mirror/spice__spice-common,Fantu/spice-common,elmarco/spice-common,Fantu/spice-common,elmarco/spice-common,SPICE/spice-common,elmarco/spice-common,fgouget/spice-common,freedesktop-unofficial-mirror/spice__spice-common,fgouget/spice-common