dvdplayer: drop StreamLock section that doesn't protect anything anymore
dvdplayer: drop unused last sub variable
dvdplayer: drop some old OnExit debug logs
dvdplayer: drop parameter from CheckPlayerInit that is part of other
dvdplayer: factor out check for selected stream
dvdplayer: add wrapper around Open(*)Stream based on CCurrentStream

This allows several code deduplifications.
Revert "[pvr] provide fps hint from pvr demux if available"

Hints is already filled with rate/scale from the construction
of the hints object from the stream.

This reverts commit dd237e82e0149d305fd0886485dc78252389ee16.
dvdplayer: factor out common code from Open(*)Stream
dvdplayer: factor better stream checks
dvdplayer: factor out stream change detection
dvdplayer: make sure we setup changes variable properly on open
dvdplayer: add generic interface to dvdplayer stream players
dvdplayer: generalize Close(*)Stream functions
dvdplayer: factor out part of openstream code
dvdplayer: don't signal audio started before we have output a packet
dvdplayer: drop try catch blocks that should never be hit

We don't throw exceptions in dvdplayer so these would never hit.

Note. I've skipped re-indenting for now since the diff would be
unreadable and history would be harder to track. Can be done as
a purely cosmetic change later.
Merge pull request #4737 from elupus/dvdrefactor

dvdplayer: refactor dvdplayer to reduce duplicate code