lavf: use AVStream.discard to disable queueing attached pictures.

libavformat/utils.c

@@ -519,7 +519,8 @@ static void queue_attached_pictures(AVFormatContext *s)
 {
     int i;
     for (i = 0; i < s->nb_streams; i++)
-        if (s->streams[i]->disposition & AV_DISPOSITION_ATTACHED_PIC) {
+        if (s->streams[i]->disposition & AV_DISPOSITION_ATTACHED_PIC &&
+            s->streams[i]->discard < AVDISCARD_ALL) {
             AVPacket copy = s->streams[i]->attached_pic;
             copy.destruct = NULL;
             add_to_pktbuf(&s->raw_packet_buffer, &copy, &s->raw_packet_buffer_end);