x86inc: Make ym# behave the same way as xm#

x264 commit 0997c288be10
cmake: prevent warnings from recent builds of cmake

cmake really should ignore cmake_policy(SET foo) if foo is not yet supported,
so every cmake user doesn't have to check the exact version which introduced
that backward compatibility option.. but...
cmake: when x86 arch is detected, set gcc -march=i686 globally

This enables a number of cleanups in the internal cmake scripts
cmake: remove two MSVC warnings overrides, HM code has been somewhat sanitized
cmake: remove two MSVC warnings overrides, HM code has been somewhat sanitized
fix
frameencoder: use macro MAX_MAX_QP
asm: code for addAvg luma and chroma all sizes
follow x264's keyframe-min logic [CHANGES OUTPUTS] (closes #24)

If no --keyint-min is specified, default to max/10, and clamp the value to
between [1, max / 2 + 1].  This allows x265 to insert I frames when scene cuts
are detected between keyframe-min and keyframe-max
cmake: treat empty CMAKE_SYSTEM_PROCESSOR as x86 (fixes #25)
common: change X265_MALLOC macro to return typed pointer

One less opportunity for a stupid mistake
Merge
assembly code for intra_pred_ang8_5
yuv: skip frames one at a time to prevent offset overflow
slicetype: fix cuTree mv indexing (bug found by herman.chen@rock-chips.com)

This drops the bitrate almost 20% and the SSIM from 0.4-0.9 dB.  I believe this
needs rebalancing.
weightp: fix hash mismatch when --ref > 3
WeightPrediction: Do not use lowres MV/MVcost for invalid MVs/MVcosts
slicetype: issue EMMS before returning a thread to the work pool
slicetype: reorg to make frame cost estimates re-entrant (for RC and WP)

* moves frame cost calculations into a separate class deriving from WaveFront
* frames[] array now always declared on stack for better re-entrant behavior
* re-orders functions in slicetype.cpp for clarity
* internal methods were made protected, for documentation purposes only
* fixes a few minor problems discovered during the reorg
* removes deprecated ReferencePlanes.unweightedFPelPlane
slicetype: upgrade frame cost variables to uint64_t