Edward Hervey authored Jun 05, 2018 and Edward Hervey committed Jun 05, 2018

We need all relevant events of a segment to have consistent seqnum:
* GST_EVENT_SEGMENT
* GST_EVENT_EOS

If we are push-based and create a new segment, use the same seqnum
as the upstream event.

If we are pull-based, use the seqnum of that newly created segment
event everywhere