avformat/m4vdec: mark as possibly containing discontinuities

This will be needed for the resolution change mpeg4 test
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/m4vdec.c

@@ -56,5 +56,5 @@ static int mpeg4video_probe(AVProbeData *probe_packet)
     return 0;
 }
 
-FF_DEF_RAWVIDEO_DEMUXER(m4v, "raw MPEG-4 video", mpeg4video_probe, "m4v",
-                        AV_CODEC_ID_MPEG4)
+FF_DEF_RAWVIDEO_DEMUXER2(m4v, "raw MPEG-4 video", mpeg4video_probe, "m4v",
+                         AV_CODEC_ID_MPEG4, AVFMT_GENERIC_INDEX | AVFMT_TS_DISCONT)