remove unnecessary -1 from snprintf len

Originally committed as revision 11009 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/mp3.c

@@ -585,7 +585,7 @@ static int mp3_write_header(struct AVFormatContext *s)
     char yeartxt[10];
 
     if(s->track)
-        snprintf(tracktxt, sizeof(tracktxt) - 1, "%d", s->track);
+        snprintf(tracktxt, sizeof(tracktxt)    , "%d", s->track);
     if(s->year)
         snprintf( yeartxt, sizeof(yeartxt)     , "%d", s->year );