Merge commit 'e46a6fb7732a7caef97a916a4f765ec0f779d195'

* commit 'e46a6fb7732a7caef97a916a4f765ec0f779d195':
  avconv: Check that muxing_queue exists before reading from it

Mostly noop. This was fixed in FFmpeg in 7f7c494a3.

The merge makes the cosmetics match but does not include the weird
av_log().

Merged-by: Clément Bœsch <cboesch@gopro.com>

ffmpeg.c

@@ -555,12 +555,14 @@ static void ffmpeg_cleanup(int ret)
         avcodec_free_context(&ost->enc_ctx);
         avcodec_parameters_free(&ost->ref_par);
 
-        while (ost->muxing_queue && av_fifo_size(ost->muxing_queue)) {
-            AVPacket pkt;
-            av_fifo_generic_read(ost->muxing_queue, &pkt, sizeof(pkt), NULL);
-            av_packet_unref(&pkt);
+        if (ost->muxing_queue) {
+            while (av_fifo_size(ost->muxing_queue)) {
+                AVPacket pkt;
+                av_fifo_generic_read(ost->muxing_queue, &pkt, sizeof(pkt), NULL);
+                av_packet_unref(&pkt);
+            }
+            av_fifo_freep(&ost->muxing_queue);
         }
-        av_fifo_freep(&ost->muxing_queue);
 
         av_freep(&output_streams[i]);
     }