avformat/vqf: check a few more bits in probe

Fixes probetest failure
The threshold is choosen so that a all printale ascii string will never be
detected as vqf
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/vqf.c

@@ -43,6 +43,9 @@ static int vqf_probe(AVProbeData *probe_packet)
     if (!memcmp(probe_packet->buf + 4, "00052200", 8))
         return AVPROBE_SCORE_MAX;
 
+    if (AV_RL32(probe_packet->buf + 12) > (1<<27))
+        return AVPROBE_SCORE_EXTENSION/2;
+
     return AVPROBE_SCORE_EXTENSION;
 }