dont fail immediately when a somehow broken track is detected, some tracks might be good, fix mi2_vorbis51.mp4

Originally committed as revision 8512 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/mov.c

@@ -1508,7 +1508,7 @@ static int mov_read_header(AVFormatContext *s, AVFormatParameters *ap)
         if(!sc->stts_count || !sc->chunk_count || !sc->sample_to_chunk_sz ||
            (!sc->sample_size && !sc->sample_count)){
             av_log(s, AV_LOG_ERROR, "missing mandatory atoms, broken header\n");
-            return -1;
+            continue;
         }
         if(!sc->time_rate)
             sc->time_rate=1;