Add entry for Dirac codec.

Patch by Anuradha Suraparaju anuradha rd bbc co uk

Originally committed as revision 14151 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/riff.c

@@ -160,6 +160,7 @@ const AVCodecTag codec_bmp_tags[] = {
     { CODEC_ID_VMNC,         MKTAG('V', 'M', 'n', 'c') },
     { CODEC_ID_TARGA,        MKTAG('t', 'g', 'a', ' ') },
     { CODEC_ID_CLJR,         MKTAG('c', 'l', 'j', 'r') },
+    { CODEC_ID_DIRAC,        MKTAG('d', 'r', 'a', 'c') },
     { CODEC_ID_NONE,         0 }
 };