dvbrecording: Fix missing PCR on stream recordings.

The ISO/IEC standard 13818-1 or ITU-T Rec. H.222.0 standard allow transport
vendors to place PCR (Program Clock Reference) on a different PID.

This patch adds it recording to file.

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>