Make the MP3 probe weakly claim all files with ID3v2 tags to fix regressions on

files with very large tags.

Originally committed as revision 17008 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/mp3.c

@@ -391,6 +391,7 @@ static int mp3_read_probe(AVProbeData *p)
     if   (first_frames>=3) return AVPROBE_SCORE_MAX/2+1;
     else if(max_frames>500)return AVPROBE_SCORE_MAX/2;
     else if(max_frames>=3) return AVPROBE_SCORE_MAX/4;
+    else if(buf0!=p->buf)  return AVPROBE_SCORE_MAX/4-1;
     else if(max_frames>=1) return 1;
     else                   return 0;
 }