[x265] [PATCH 0 of 2 ] enable psycho-visual optimizations by default

[Steve Borho]

This series enables psy-rd and psy-rdoq by default after auto-tuning psy-rd base on the current CTU's QP, in order to avoid serious artifacting. I would love to hear feedback about whether the default values are ok, and whether the threshold QP values are ok. Suggestions welcome.  These should be the last two changes on default prior to merging to stable for the 1.5 release