Kokoro: Correct the `build_file' path to build.sh

License headers: s/Google/The Khronos Group

This was a copy-paste screwup, where the first line of the copyright had the company name was updated, but the company name mid way though was not.

Add license checking continuous and presubmit tests

Fix GLSLANG_IS_SHARED_LIBRARY define

The `license-checker` is a tool that verifies each file has contains a permitted license header.

See https://github.com/ben-clayton/license-checker for more information.

It was incorrectly always being set, causing linker warnings for MSVC builds.
Also simplify the preprocessor nesting in `glslang\Public\ShaderLang.h`

Add copyright headers to build files and scripts.
Simplifies automated scanning for bad license headers.

HLSL: Fix #pragma pack_matrix(row_major) not work on global uniforms

glslang: Only export public interface for SOs

Location validation, with update to SPIR-V tools validating location

This introduces five new "Validation failures":
- baseResults/hlsl.semantic.vert: issue with gl_ClipDistance/CullDistance
- baseResults/spv.430.vert: issue gl_ClipDistance
- baseResults/spv.450.tesc: still unknown
- baseResults/spv.dataOut.frag: gl_FragData should not be supported, problem with front end
- baseResults/spv.meshShaderPerViewUserDefined.mesh: seems okay, maybe a problem with SPIRV-Tools

This adds or changes binding/location decorations in 100s of shaders.
It also allows more output (spv.register.autoassign.rangetest.frag)
due to allowing ioMap() to fail.

Add additional licenses in use to LICENSE.txt

Ideally we'd unify the licenses in use by changing the licenses in the file headers to BSD-3-clause.

Until then, let's correctly list all the licenses currently in use.

Issue: #2305

Related to https://github.com/KhronosGroup/SPIRV-Cross/issues/1414.
The real problem is either using DX10 semantics for DX9 or missing
functionality in DX10 parsing.

SPV: RelaxedPrecision: use the result precision for texture sampling.

SPV: RelaxedPrecision: Generalize fix #2293 to cover more operations.

Default to `-fvisibility=hidden`, and annotate the public glslang interface with `GLSLANG_EXPORT` to change the visibility of these cherry-picked symbols to default.
This is also used by Windows builds for `__declspec(dllexport)`-ing the public DLL interface.

This allows us to classify API changes into those that are publicly backwards compatible, and those that are not.

Note that `libSPIRV` will likely need similar treatment.

Issues: #2283, #1484

CMake: break up glslang into smaller static libs

Add `GenericCodeGen` and `MachineIndependent` static library targets.
Privately import both of these into the `glslang` target.
Privately import `MachineIndependent` into the  `SPIRV` target.

This is done to break the dependency of `libglslang.so` non-public APIs from `libspirv.so`,
which will become problematic once `glslang` hides its non-public symbols.

| File                      | Before     |     After  |
|---------------------------|-----------:|-----------:|
| `libGenericCodeGen.a`     |  -         |   `527716` |
| `libglslang.a`            | `68175944` |   `512938` |
| `libHLSL.a`               |     `1428` |     `1428` |
| `libMachineIndependent.a` |  -         | `67132202` |
| `libOGLCompiler.a`        |    `75908` |    `75908` |
| `libOSDependent.a`        |    `23768` |    `23768` |
| `libSPIRV.a`              | `15710210` | `15710210` |
| `libSPVRemapper.a`        |  `3250894` |  `3250894` |

| File                                    | Before     |     After  |
|-----------------------------------------|-----------:|-----------:|
| `libglslang-default-resource-limits.so` |   `117032` |   `117032` |
| `libglslang.so`                         | `22380688` | `22368216` |
| `libHLSL.so`                            |     `7520` |     `7520` |
| `libOGLCompiler.a`                      |    `75908` |    `75908` |
| `libOSDependent.a`                      |    `23768` |    `23768` |
| `libSPIRV.so`                           |  `7288336` | `28151016` |
| `libSPVRemapper.so`                     |  `1940208` |  `1940208` |

Issues: #2283, #1484

CMake: Compile with -fPIC when building SOs

Fix #2298.

The AST has two precisions, an operation precision and a result precision.
Actual use of GLSL with mediump samplers wants the result precision, so
pick that up instead of the operation precision.

CMake: Error on unresolved symbols

This simplifies and enforces use of precision in many more places,
to help avoid accidental loss of RelaxedPrecision through intermediate
operations. Known fixes are:
- ?:
- function return values with mis-matched precision
- precision of function return values when a copy was needed to fix types

Remove root kokoro/linux-*-cmake configs

Fixed GCC -Wunused-parameter in hlslParseables.cpp.

Warnings before fix:

[3/7] Building CXX object glslang/CMakeFiles/glslang.dir/HLSL/hlslParseables.cpp.o
../glslang/HLSL/hlslParseables.cpp: In function ‘bool {anonymous}::IsValid(const char*, char, char, char, char, int, int)’:
../glslang/HLSL/hlslParseables.cpp:334:45: warning: unused parameter ‘retOrder’ [-Wunused-parameter]
  334 | inline bool IsValid(const char* cname, char retOrder, char retType, char argOrder, char argType, int dim0, int dim1)
      |                                        ~~~~~^~~~~~~~
../glslang/HLSL/hlslParseables.cpp:334:60: warning: unused parameter ‘retType’ [-Wunused-parameter]
  334 | inline bool IsValid(const char* cname, char retOrder, char retType, char argOrder, char argType, int dim0, int dim1)
      |                                                       ~~~~~^~~~~~~
../glslang/HLSL/hlslParseables.cpp:334:89: warning: unused parameter ‘argType’ [-Wunused-parameter]
  334 | inline bool IsValid(const char* cname, char retOrder, char retType, char argOrder, char argType, int dim0, int dim1)
      |                                                                                    ~~~~~^~~~~~~
../glslang/HLSL/hlslParseables.cpp:334:112: warning: unused parameter ‘dim1’ [-Wunused-parameter]
  334 | inline bool IsValid(const char* cname, char retOrder, char retType, char argOrder, char argType, int dim0, int dim1)
      |                                                                                                            ~~~~^~~~

Without this embedding static libraries into shared libraries may result in link time errors.

Issue: #2283

Issue: #1484

These have been superseded by the `static` and `shared` variants in the respective subdirectories.

Issue: #2283

Kokoro: Split linux cmake cfgs into static/shared

Fix #2293: Get correct RelaxedPrecision settings for various ways of passing arguments to formal parameters.

When arguments are copied to make space for a writable formal parameter,
and the formal parameter is relaxed precision, make the copy also
relaxed precision.

Track whether formal parameters declare reduced precision and match
that with arguments, and if they differ, make a copy to promote the
precision.

Allows for testing of generation of both static libraries and shared objects.

The old configs are staying in place until I'm confident everything is working correctly.

Issues: #1421, #1484, #2283