libvorbisenc: Fix assignments in if()

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

libavcodec/libvorbisenc.c

@@ -305,7 +305,7 @@ static int oggvorbis_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
             av_log(avctx, AV_LOG_ERROR, "error in vorbis_analysis_wrote()\n");
             return vorbis_error_to_averror(ret);
         }
-        if ((ret = ff_af_queue_add(&s->afq, frame) < 0))
+        if ((ret = ff_af_queue_add(&s->afq, frame)) < 0)
             return ret;
     } else {
         if (!s->eof)