[omxplayer] Don't flush queued data on general reset

We were flushing the queue of data to gpu (which can be a number of seconds worth) on a general reset.
However this is generated on inoccuous events like a chapter change in dvd playback.

This results in a few seconds loss of audio, and a temporary audio/video sync error
[PVR] initial support for sub channel numbers. display only. only works with 'using backend channel numbers' enabled
[PVR] bump add-ons
DXVA: factor out interface to dxva decoder into singleton
DXVA: only allow a single dxva decoder to be opened
DXVA: refcount decoder on get/release buffer
[curl] redact effective URL
[pvr] fix destructor visibility to allow polymorphic deletion

This fixes the polymorphic deletion in CGUIWindowPVRBase.
Merge pull request #5290 from opdenkamp/subchannels

PVR: initial support for sub channel numbers
Merge pull request #5338 from xhaggi/pvr-fix-destructor-visibility

[pvr] fix destructor visibility to allow polymorphic deletion
Merge pull request #5335 from FernetMenta/dxva

DXVA: fixes related to ffmpeg
Merge pull request #5337 from wsnipex/curl_real_url

[curl] redact effective URL
Merge pull request #5240 from popcornmix/generalreset

[omxplayer] Don't flush queued data on general reset