Bump libx265 to version 0.8.

Miscellaneous fixes and improvements, and simplify
the patch to fix multiple inclusions of x265.h


git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@6114 b64f7644-9d1e-0410-96f1-a4d463321fa5
QSV: fix preset names for Ivy Bridge and earlier.


git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@6115 b64f7644-9d1e-0410-96f1-a4d463321fa5