Add codec ID for Shorten audio.

Originally committed as revision 6680 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/riff.c

@@ -196,6 +196,7 @@ const CodecTag codec_wav_tags[] = {
     { CODEC_ID_FLAC, MKTAG('f', 'L', 'a', 'C') },
     { CODEC_ID_TTA, MKTAG('T', 'T', 'A', '1') },
     { CODEC_ID_WAVPACK, MKTAG('W', 'V', 'P', 'K') },
+    { CODEC_ID_SHORTEN, MKTAG('s', 'h', 'r', 'n') },
 
     // for NuppelVideo (nuv.c)
     { CODEC_ID_PCM_S16LE, MKTAG('R', 'A', 'W', 'A') },