wv: use right function to read block_samples

Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavformat/wv.c

@@ -341,7 +341,7 @@ static int wv_read_packet(AVFormatContext *s, AVPacket *pkt)
     pkt->stream_index = 0;
     wc->block_parsed  = 1;
     pkt->pts          = wc->soff;
-    block_samples     = AV_RN32(wc->extra);
+    block_samples     = AV_RL32(wc->extra);
     if (block_samples > INT32_MAX)
         av_log(s, AV_LOG_WARNING,
                "Too many samples in block: %"PRIu32"\n", block_samples);