Support AAC audio in AVI with tag 0xff

Patch by David Conrad ( davedc_ | umbc edu )

Originally committed as revision 5963 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/riff.c

@@ -176,6 +176,7 @@ const CodecTag codec_wav_tags[] = {
     { CODEC_ID_WMAV1, 0x160 },
     { CODEC_ID_WMAV2, 0x161 },
     { CODEC_ID_AAC, 0x706d },
+    { CODEC_ID_MPEG4AAC, 0xff },
     { CODEC_ID_VORBIS, ('V'<<8)+'o' }, //HACK/FIXME, does vorbis in WAV/AVI have an (in)official id?
     { CODEC_ID_SONIC, 0x2048 },
     { CODEC_ID_SONIC_LS, 0x2048 },