The previous fix for this only enabled HLSL internally in glslang which
means that dependent using HLSL, for example shaderc, failed
compilation.

GN build (for Chromium): enable HLSL

GLSL: Inherit memory qualifiers, both declaratively and in execution.

Fixes #1870, probably others.

Fix conformance with -Wextra-tokens

Web:  Create a very small-footprint glslang for web use.

Saved about 21K, size down to 380K of MSVC x86 code.
Fixed one bug that needs to be looked at on the master branch:
The test for needing a Vulkan binding has a bug in it, "!layoutAttachment"
which does not mean "no layoutAttachment", because that is non-zero.
This is why some test and test results changed.

added a few more HLSL flag tests.  This was mostly focused on the SPV generator.
Saves about 17K.

Saves about 6.5K

Saves 2.5K, and design is better.

Saves another 20K.

This saves another 40K of x86 binary, which is about 13% of the target size.

Saves about 9K.

About 60K smaller (20% the target size is these units of 300K).
Over 300 fewer #ifdef.

This adds a new glslang.m4 file that needs to be processed by m4 to get
the glslang.y file needed by bison.  See comment in glslang.m4 for more
detail.

This updates the updateGrammar script to do the .m4 -> .y processing,
to conditionally exclude grammar not needed for the web build.

About 50 fewer #ifdefs.
About 14K smaller.
Note, the base size is ill-defined due to optimizer settings (size vs. performance),
compression, and target architecture.  Some recent %'s are accidentally reported as
3X the real savings.  Early %'s were accurate.  What matters though is that each
step got worthwhile gains, and what the final size ends up being.

Focus was on the front end (not SPIR-V), minus the grammar.
Reduces #ifdef count by around 320 and makes the web build 270K smaller,
which is about 90% the  target size.

The grammar and scanner will be another step, as will the SPIR-V backend.
This makes heavy use of methods #ifdef'd to return false as a global way
of turning off code, relying on C++ DCE to do the rest.

Doing this much saved about 11.5K, including adding all the infrastructure.

Save about 100K.

N.B.: This is done by eliminating a function call, at a high level,
not by #ifdef'ing a bunch of code.

Also, removed no longer needed *_EXTENSION #ifdef in the code not
needed by GLSLANG_WEB.

This saves about 7K.
By changing just a few methods to be compile-time known, a bunch of
scattered code becomes DCE.

Saves about 3K.

For the smallest builds, google tests will not be present, in
addition to a large number of tests not being capable of running.

make glslang.js easy to use and work on node, and related changes

Add WASM build target for Web version of glslang

This adds build rules to support generating a WASM binary to be used
on the web. The API exposed to web applications is definated in the
new glslang.js.cpp file.