memory leak fix by (Tom Dexter <devel at www dot digitalaudiorock dot com>)

Originally committed as revision 2216 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/utils.c

@@ -555,6 +555,7 @@ static void flush_packet_queue(AVFormatContext *s)
         if (!pktl) 
             break;
         s->packet_buffer = pktl->next;
+        av_free_packet(&pktl->pkt);
         av_free(pktl);
     }
 }