frameencoder: use x265_emms() prior to double QP clipping for VBV
frameencoder: use simple shifts to scale 2-pass CU type counters

the cu type counters are summed at the end and turned into percentages, so
it doesn't matter what base unit is used, only that each depth has 4x the
value as depth+1
copy_cnt_4: enable fast non zero coefficient count path
copy_cnt_4: combine mova and paddb to reduce code size, same speedup
copy_cnt_4: faster AVX2 code
copy_cnt_8 AVX2 asm code, as per new interface
search: return distortion from xIntraCodingLumaBlk, do not pass by reference
search: return distortion from xRecurIntraChromaCodingQT, do not pass by ref
search: return distortion from xIntraCodingChromaBlk, do not pass by ref
search: return distortion from xRecurIntraCodingQT
search: pass depthRange uniformly as uint32_t depthRange[2]

effectively the same as uint32_t but compilers and debuggers can often do more
with the length info. plus it just makes the code more readable
search: return distortion from xEstimateResidualQT
search: don't pass a zeroDistortion pointer if you don't want the answer
search: fix camel case of residualQTIntraChroma
analysis: modified compressInterCU_rd0_4() with CU-specific information