CInterface: added _BIT suffix to glslang_messages_t and glslang_reflection_options_t, fixed const-correctness

Update spriv-tools known good

Fix #2020: PR #1977 broke HLSL member consistency, this fixes it.

using an unitialized member.  This commit consistently does not use those
HLSL members unless ENABLE_HLSL is on.

Fix: #2014: Don't do "extension-on && version >= ..." keyword checks.

Fix #2007: Fix a couple relative header paths in header files.

Keywords should only have tests like "extension-on || version >= ...", or
"extension-off && version <= ...".

Remove glslang::pool_allocator::setAllocator

TPoolAllocator is not copy assignable, so this setter could never have
been used. After a recent change (878a24ee2), new versions of Clang
reject this code outright.

Implement INTEL_shader_integer_functions2

v2: Move addCapability and addExtension extension calls from
TGlslangToSpvTraverser::createBinaryOperation to
TGlslangToSpvTraverser::visitAggregate.  Suggested by JohnK.

The changes to glslang/glslang/MachineIndependent/ParseHelper.cpp exist
purely to prevent even more instances of "warning: enumeration value
‘EOp...’ not handled in switch"

v2: Remove 8-bit types.  Overzealous copy-and-paste led to adding
support for a bunch of types that the extension doesn't actually enable.

v3: Update expected test results file.  Just changing an expected
results file to make a test pass seems sketchy to me, but I'm not sure
what else to do.

v4: Add missing entry for EOpAbsDifference in
TOutputTraverser::visitBinary.  Noticed by JohnK.

Update README.md to include other test requirements

Knowing this in advance would have saved me some time.

Fix #1981

Copy over incoming units localSize if it's set, and this->localSize is not set
Also fix overwritting localSizeSpecId if it's already been set.

Fix construction issue for 8 and 16 bit types.

Respect CMAKE_INSTALL_LIBDIR in installed CMake files

There is a flag to disable the SPVRemapper during the GLSLang build.
That flag is check in some, but not all spots so if you try to build
with SPVRemapper disabled you get CMake errors and compile errors.

This CL fixs up the build so building with -DENABLE_SPVREMAPPER=0 will
complete correclty.

Fixes #1965

HLSL: Fix #1976: Don't let ENABLE_HLSL change struct/class layout.

HLSL: Fix #1960: fmod() was not converting int args to float.