avformat/westwood_aud: replace != 0 error check by <0

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/westwood_aud.c

@@ -151,7 +151,7 @@ static int wsaud_read_packet(AVFormatContext *s,
            Specifically, this is needed to signal when a packet should be
            decoding as raw 8-bit pcm or variable-size ADPCM. */
         int out_size = AV_RL16(&preamble[2]);
-        if ((ret = av_new_packet(pkt, chunk_size + 4)))
+        if ((ret = av_new_packet(pkt, chunk_size + 4)) < 0)
             return ret;
         if ((ret = avio_read(pb, &pkt->data[4], chunk_size)) != chunk_size)
             return ret < 0 ? ret : AVERROR(EIO);