[rbp/omxplayer] do not reopen the resample context for each frame.

I think this doesn't tend to happen on Pi now, as AV_SAMPLE_FMT_S16 and AV_SAMPLE_FMT_FLTP bypass the resampler,
but best to fix it if some obscure codec returns something else.

See #2873
Merge pull request #2881 from popcornmix/avoid_resample_init

[rbp/omxplayer] do not reopen the resample context for each frame.
Remove misrepresented parameter from IAddon::Clone(), CAddon::CAddon(const CAddon&) and related subclass methods
Move member initializers from CRepository::Clone() to copy constructor.

Also adds missing m_hashes member.
Move CScreensaver cloning to new method, CScreensaver::Clone()

CScreensaver::Clone() is virtual and overrides IAddon::Clone()