activate gif decoder, seems to work fine on showdown2.mov

Originally committed as revision 6767 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/mov.c

@@ -81,7 +81,7 @@ static const CodecTag mov_video_tags[] = {
     { CODEC_ID_MJPEGB, MKTAG('m', 'j', 'p', 'b') }, /* Motion-JPEG (format B) */
     { CODEC_ID_MJPEG, MKTAG('A', 'V', 'D', 'J') }, /* MJPEG with alpha-channel (AVID JFIF meridien compressed) */
 /*    { CODEC_ID_MJPEG, MKTAG('A', 'V', 'R', 'n') }, *//* MJPEG with alpha-channel (AVID ABVB/Truevision NuVista) */
-/*    { CODEC_ID_GIF, MKTAG('g', 'i', 'f', ' ') }, *//* embedded gif files as frames (usually one "click to play movie" frame) */
+    { CODEC_ID_GIF, MKTAG('g', 'i', 'f', ' ') }, /* embedded gif files as frames (usually one "click to play movie" frame) */
 /* Sorenson video */
     { CODEC_ID_SVQ1, MKTAG('S', 'V', 'Q', '1') }, /* Sorenson Video v1 */
     { CODEC_ID_SVQ1, MKTAG('s', 'v', 'q', '1') }, /* Sorenson Video v1 */