We need separate concepts for
 - total set of extensions ever enabled, for the back end
 - current state of extensions, for parsing
 - the set of features currently enabled for building the AST

This detangles incorrect conflation of HLSL with GLSL extensions,
defers asking expensive questions until it's time to ask, and removes
some dead code.

The scalar type was already the basic type passed in.

Also factored out of this the checking of extensions for 8/16-bit stuff.
This code seems wrong in several ways, but for now just documenting it.

See #2366 for detail.

Build/Test: Dropping VS 2013 allows using the latest googletests

These have a new spelling: INSTANTIATE_TEST_CASE_P -> INSTANTIATE_TEST_SUITE_P

Use GLSLANG_ANGLE to strip features to what ANGLE requires

Revert changes that migrate to `thread_local`.

This change strips a few features similar to GLSLANG_WEB but doesn't
remove every detail like the latter.  It also hardcodes profile/version
to core/450.

In particular, TBuiltIns::initialize is specialized to remove most of
what is not supported or won't be supported by ANGLE.  The result of
this function is parsed with TParseContext::parseShaderStrings which is
a performance bottleneck.

This change shaves about 300KB off of ANGLE's binary size and reduces
the cost of SetupBuiltinSymbolTable to nearly a sixth.
Signed-off-by: Shahbaz Youssefi <ShabbyX@gmail.com>

iOS 8 does not support `thread_local`, which is still in use.
Another approach will have to be found.

This change is a revert of the following changes:

a3845240 - "Simplify PoolAlloc with use of thread_local."
abf92c80 - "Deprecate InitializeDll functions"
33585c87 - "Limit visibility of symbols for internal libraries"

Issue: #2346

Avoid spurious warning about uninit var

Update spirv-tools known-good to most recent stable

Add changes for SPV_EXT_shader_atomic_float_add

Limit visibility of symbols for internal libraries

Also remove `SPIRV/doc.cpp` from the `SPVRemapper` target as this
is part of `SPIRV`, causing ODR violations. Instead have
`SPVRemapper` link against `SPIRV`.

Fixes ODR violations.

Simplify PoolAlloc by using `thread_local`

also search global sequences for live variables

These were only used for TThreadPool, which now uses `thread_local`.

glslang is using C++ 11, which has first class support for variables of the `thread_local` storage class.

By dropping the use of the `OS_[GS]etTLSValue`, we can simplify the logic, and have it support a thread-local default allocator if none is provided.

Issue: #2346

Finalize glslang 10.15.3847, start glslang 11, drop support for VS2013

when traversing the AST to find live UBOs etc, also traverse
references to global module-level variables, incase they are
being filled in from UBOs etc.

This was scheduled for today - 20th July 2020.

Updates Appveyor configs to use VS2015 instead.

Update license-checker.cfg with simplified rules

`license-checker` has been updated to support `**` wildcards simplifying the ruless, and multiple license configs.

Add a new config for the bison generated files to ensure their licenses don't change.

Add new rules for update of license-checker

`license-checker` will be updated to support `**` based wildcards. As part of this, `license-checker` will now traverse into subdirectories that would previously be excluded when the parent directory is excluded.

This change adds new rules that work with both the old version and new, to ease migration.

GLSL/SPV: Propagaet precision qualifier from function to return value.