Add flag to mark demuxers that can output discontinuous timestamps.

(could also be added to muxers if someone wants)

Originally committed as revision 14777 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/mpeg.c

@@ -586,5 +586,5 @@ AVInputFormat mpegps_demuxer = {
     NULL,
     NULL, //mpegps_read_seek,
     mpegps_read_dts,
-    .flags = AVFMT_SHOW_IDS,
+    .flags = AVFMT_SHOW_IDS|AVFMT_TS_DISCONT,
 };