mpegts: always parse pcr

Previously pcr transmitted without payload but as part of the video stream was
not parsed.

Signed-off-by: Marton Balint <cus@passwd.hu>
Merge remote-tracking branch 'cus/stable'

* cus/stable:
  mpegts: always parse pcr

Merged-by: Michael Niedermayer <michaelni@gmx.at>