avformat/audiointerleave: Fix memleak

If ff_interleave_add_packet failed, the content of the newly created
packet new_pkt would leak.

Also, it is unnecessary to zero-initialize a packet that will be put
into av_new_packet lateron as the latter already initializes the packet.
Therefore this has been removed, too.
Reviewed-by: Marton Balint <cus@passwd.hu>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavformat/audiointerleave.c

@@ -134,11 +134,13 @@ int ff_audio_rechunk_interleave(AVFormatContext *s, AVPacket *out, AVPacket *pkt
     for (i = 0; i < s->nb_streams; i++) {
         AVStream *st = s->streams[i];
         if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
-            AVPacket new_pkt = { 0 };
+            AVPacket new_pkt;
             while ((ret = interleave_new_audio_packet(s, &new_pkt, i, flush)) > 0) {
-                if ((ret = ff_interleave_add_packet(s, &new_pkt, compare_ts)) < 0)
+                if ((ret = ff_interleave_add_packet(s, &new_pkt, compare_ts)) < 0) {
+                    av_packet_unref(&new_pkt);
                     return ret;
                 }
+            }
             if (ret < 0)
                 return ret;
         }