avformat: Remove unnecessary av_packet_unref()

Since bae8844e the packet will always be unreferenced when a demuxer
returns an error, so that a lot of calls to av_packet_unref() in lots of
demuxers are now redundant and can be removed.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Signed-off-by: Marton Balint <cus@passwd.hu>

libavformat/ape.c

@@ -419,7 +419,6 @@ static int ape_read_packet(AVFormatContext * s, AVPacket * pkt)
     AV_WL32(pkt->data + 4, ape->frames[ape->currentframe].skip);
     ret = avio_read(s->pb, pkt->data + extra_size, ape->frames[ape->currentframe].size);
     if (ret < 0) {
-        av_packet_unref(pkt);
         return ret;
     }