Merge commit '33c859c142'

* commit '33c859c142':
  lavf: ignore attachment streams for interleaving purposes

Conflicts:
	libavformat/avformat.h
	libavformat/internal.h
	libavformat/mux.c

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

libavformat/utils.c

@@ -3480,6 +3480,7 @@ void avformat_free_context(AVFormatContext *s)
     av_freep(&s->chapters);
     av_dict_free(&s->metadata);
     av_freep(&s->streams);
+    av_freep(&s->internal);
     av_free(s);
 }