Cycles: enable /arch:AVX in msvc 11 and later versions for avx kernel
Cycles: enable /arch:AVX in msvc 11 and later versions for avx kernel

This enables VEX-encoding in AVX kernel for windows msvc builds and gives 5-10% speedup for different scenes.

Reviewers: juicyfruit, dingto, brecht

Reviewed By: brecht

CC: brecht

Differential Revision: https://developer.blender.org/D284

tangent-opensource/coreBlackbird,tangent-opensource/coreBlackbird,pyrochlore/cycles,pyrochlore/cycles,tangent-opensource/coreBlackbird,pyrochlore/cycles