pixel: stop building 16x16, 16x8, and 8x16 intrinsic primitives
asm: quit instantiating functions which are not necessary

Re-order functions for more clarity
pixelharness: report sad, sad_x3, and sad_x4 scores together
primitives: move small block sa8d_inter setup to primitives.cpp

This hack didn't belong in the assembly setup function
asm: use x265_pixel_satd_8x4_xop for p.satd[PARTITION_16x4] for 32 bit builds

On 64bit builds, we have native sse2 functions
primitives: setup square sa8d_inter function pointers from sa8d block pointers
primitives: fixup 12x16 and 16x2 sa8d_inter pointers

32x12 isn't used but 12x16 and 16x12 are (for AMP)
primitives: fix off-by one initialization of primitives
pixel: add back intrinsics for sad_x3_4x16 and sad_x4_4x16

These routines do not yet have assembly code
testbench: fix off-by one initialization of primitives
asm: simplify generation of sa8d_inter functions from 8x8 and 16x16 blocks
asm: cleanup the assignment of SSD primitives
pixel: drop SSE primitives that have assembly
asm: don't build wrappers for functions with intrinsic implementations
pixel: add missing sse_pp_12x16, untemplatize others
pixel: fix HIGH_BIT_DEPTH builds
pixel: simplify sad_16 to make it easier to maintain
pixel: simplify sad_x3_16 and sad_x4_16 to make them easier to maintain
asm: simplify setup of HEVC partitions for SATD primitives
pixel: fix eoln damage to pixel-avx2.cpp