[x265] upcoming merge

[Steve Borho]

We have a number of AVX2 optimizations that have been collected together
in a another repository: https://bitbucket.org/multicoreware/x265-AVX2

We plan to merge in those changesets fairly soon. They give about a 6%
gain in performance on AVX2 capable CPUs.

In the interests of not spamming the list, I won't send all of those
assembly patches here. If you like to review the AVX2 assembly, pull
from that URL. Let me know if you have any concerns.

-- 
Steve Borho