always write footer partition according to specs

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@15100 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavformat/mxfenc.c

@@ -857,11 +857,10 @@ static int mxf_write_footer(AVFormatContext *s)
     ByteIOContext *pb = s->pb;
     int64_t byte_position= url_ftell(pb);
 
-    if (!url_is_streamed(s->pb)) {
     mxf_write_partition(s, byte_position, 0, footer_partition_key);
     put_flush_packet(pb);
+    if (!url_is_streamed(s->pb))
         mxf_update_header_partition(s, byte_position);
-    }
     mxf_free(s);
     return 0;
 }