avformat/wavdec: Increase probe_packets limit

Fixes DTS detection of b2429e5ba9.dts
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 9f576943)
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/wavdec.c

@@ -114,7 +114,7 @@ static void handle_stream_probing(AVStream *st)
 {
     if (st->codec->codec_id == AV_CODEC_ID_PCM_S16LE) {
         st->request_probe = AVPROBE_SCORE_EXTENSION;
-        st->probe_packets = FFMIN(st->probe_packets, 14);
+        st->probe_packets = FFMIN(st->probe_packets, 20);
     }
 }