Reduce probe score as it misdetects our flv file from the regression test.

The only reason why it does not break them is that flv has the same score
and happens to be first in the list.

Originally committed as revision 12834 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/vc1test.c

@@ -35,7 +35,7 @@ static int vc1t_probe(AVProbeData *p)
     if (p->buf[3] != 0xC5 && AV_RL32(&p->buf[4]) != 4)
         return 0;
 
-    return AVPROBE_SCORE_MAX;
+    return AVPROBE_SCORE_MAX/2;
 }
 
 static int vc1t_read_header(AVFormatContext *s,