testbench: port x264 stack & register check code
pixelharness: stack-check all asm pixel primitives
update x86inc.asm
primitives: nit
improve by LEA to ADD in cvt32to16_shr
cmake: export YASM_FLAGS from CMakeASM_YASMInformation.cmake

This avoids duplicate logic in other cmake scripts
move checkasm-a.asm to the test/ folder (fixes linux link)
align the stack for GCC x86_32 builds

For all threads x265 creates, align the stack immediately in the call to
threadMain().

The API calls do not appear to require an aligned stack; all primitives that
require stack aligned buffers are called from frame encoder or worker pool
threads
fixups for testbench build on Windows
TComMotionInfo: nit
correct register number in pixel-a.asm
intrapred: stack-check asm intra primitives

prune some extra memsets that were used during development
ipfilter: stack-check asm filter primitives
ipfilter: remove utterly useless comments
dct: stack-check asm transform/quant primitives
rest: move --hash into bitream options section, document error-recovery aspects
rest: loop filters, plural
rest: move --repeat-headers to bitstream options section
rest: move quality metrics section up higher
primitives: pass bool value as int to assembly

bool type is too ambiguous