add avx version for chroma_copy_ss 16x4, 16x8, 16x12, 16x16, 16x24, 16x32, 16x64 based on csp, approx 1.5x-2x speedup over SSE
asm: replace mova by movu to avoid AVX2 testbench crash in dct16, dct32, denoise_dct, its same speed on Haswell
asm: avx2 code for dct8x8
blockcopy_ss: 64x16, 64x32, 64x48, 64x64 AVX version of asm code, approx double speedup comapre to SSE
Backed out changeset: fa2f1aa1456e

This commit allocated the harness instances on the heap, thus
no longer respecting __declspec(align) directives for the member
fields. We could probably circumvent this by overloading operator new with
aligned_malloc, but I'm not sure this is good practice.

--HG--
extra : amend_source : 854213e82fa93b4606d0e1ed0b13cf550f4526f1