libavformat/mxfenc.c: added mxf opatom muxer

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/allformats.c

@@ -206,6 +206,7 @@ void av_register_all(void)
     REGISTER_DEMUXER (MVI,              mvi);
     REGISTER_MUXDEMUX(MXF,              mxf);
     REGISTER_MUXER   (MXF_D10,          mxf_d10);
+    REGISTER_MUXER   (MXF_OPATOM,       mxf_opatom);
     REGISTER_DEMUXER (MXG,              mxg);
     REGISTER_DEMUXER (NC,               nc);
     REGISTER_DEMUXER (NISTSPHERE,       nistsphere);