let vorbis decoder init too, fix mi2_vorbis51.mp4

Originally committed as revision 5223 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/mov.c

@@ -1142,6 +1142,9 @@ static int mov_read_stsd(MOVContext *c, ByteIOContext *pb, MOV_atom_t atom)
     switch (st->codec->codec_id) {
 #ifdef CONFIG_FAAD
     case CODEC_ID_AAC:
+#endif
+#ifdef CONFIG_VORBIS_DECODER
+    case CODEC_ID_VORBIS:
 #endif
     case CODEC_ID_MP3ON4:
         st->codec->sample_rate= 0; /* let decoder init parameters properly */