segment: copy metadata

Fixes Ticket2230
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/segment.c

@@ -129,6 +129,7 @@ static int segment_mux_init(AVFormatContext *s)
 
     oc->oformat            = seg->oformat;
     oc->interrupt_callback = s->interrupt_callback;
+    av_dict_copy(&oc->metadata, s->metadata, 0);
 
     for (i = 0; i < s->nb_streams; i++) {
         AVStream *st;