avformat/nut: add GIF[0]

Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavformat/nut.c

@@ -40,6 +40,7 @@ const AVCodecTag ff_nut_data_tags[] = {
 };
 
 const AVCodecTag ff_nut_video_tags[] = {
+    { AV_CODEC_ID_GIF,              MKTAG('G', 'I', 'F',  0 ) },
     { AV_CODEC_ID_XFACE,            MKTAG('X', 'F', 'A', 'C') },
     { AV_CODEC_ID_VP9,              MKTAG('V', 'P', '9', '0') },
     { AV_CODEC_ID_RAWVIDEO,         MKTAG('R', 'G', 'B', 15 ) },