mpegtsmux sends segment before caps
Since 52c419b7 from !2372 (merged) (e7d57331 from !2381 (merged) on 1.20, not yet released), mpegtsmux
can send segment before caps, leading to a misordering error.
Tsmux can mux buffers from non-PCR streams before it has output the headers it produces with the first data on the PCR stream.
Reproducer:
G_DEBUG=fatal-warnings gst-launch-1.0 \
videotestsrc timestamp-offset=1000000000 ! x264enc ! m.sink_141 \
audiotestsrc ! faac ! m.sink_142 \
mpegtsmux name=m ! fakesink
../subprojects/gstreamer/gst/gstpad.c:5337:store_sticky_event:<m:src> Sticky event misordering, got 'segment' before 'caps'
Reverting the commit resolves the problem.