spice.proto: add SPICE_MSG_MAIN_MIGRATE_END & SPICE_MSGC_MAIN_MIGRATE_END
spice.proto: add SPICE_MSG_MAIN_MIGRATE_END & SPICE_MSGC_MAIN_MIGRATE_END

(cherry picked from commit cfbd07710562e522179ae5a7085a789489a821bb branch 0.8)

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