Cosmetics : remove duplicated comment.

Originally committed as revision 21088 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/snow.c

@@ -434,7 +434,6 @@ typedef struct Plane{
 }Plane;
 
 typedef struct SnowContext{
-//    MpegEncContext m; // needed for motion estimation, should not be used for anything else, the idea is to eventually make the motion estimation independent of MpegEncContext, so this will be removed then (FIXME/XXX)
 
     AVCodecContext *avctx;
     RangeCoder c;