Remove hack in MP3 probe that was meant as a work-around for large

ID3v2 tags which no longer works since ID3v2 handling was moved to
generic code.
In addition, in caused false-positives for all files starting with
one or more 0-bytes.

Originally committed as revision 25929 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/mp3.c

@@ -68,7 +68,6 @@ static int mp3_read_probe(AVProbeData *p)
     if   (first_frames>=4) return AVPROBE_SCORE_MAX/2+1;
     else if(max_frames>500)return AVPROBE_SCORE_MAX/2;
     else if(max_frames>=4) 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;
 //mpegps_mp3_unrecognized_format.mpg has max_frames=3