Add FourCC yuvs for rawvideo (PIX_FMT_YUYV422).

Patch by Andrew Wason, rectalogic rectalogic com

Originally committed as revision 25853 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/riff.c

@@ -162,6 +162,7 @@ const AVCodecTag ff_codec_bmp_tags[] = {
     { CODEC_ID_RAWVIDEO,     MKTAG('u', 'y', 'v', '1') },
     { CODEC_ID_RAWVIDEO,     MKTAG('2', 'V', 'u', '1') },
     { CODEC_ID_RAWVIDEO,     MKTAG('2', 'v', 'u', 'y') },
+    { CODEC_ID_RAWVIDEO,     MKTAG('y', 'u', 'v', 's') },
     { CODEC_ID_RAWVIDEO,     MKTAG('P', '4', '2', '2') },
     { CODEC_ID_RAWVIDEO,     MKTAG('Y', 'V', '1', '2') },
     { CODEC_ID_RAWVIDEO,     MKTAG('U', 'Y', 'V', 'Y') },