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

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.

When a return value's type has no precision qualification (e.g., the return
expression is formed from a constructor), and the formal function return type
has a precision qualification, back propagate that from the return type to the
type of the return value's expression.

runtests: Check error codes, set LD_LIBRARY_PATH

`glslangValidator` will only return [the codes 0..6](https://github.com/KhronosGroup/glslang/blob/b481744aea1ecf52ee4591afaa0f5e270b9d1636/StandAlone/StandAlone.cpp#L117-L125). Fail the test if anything else is returned (like due to the exe crashing).

Also set `LD_LIBRARY_PATH` to contain the `lib` directory before calling glslang.

Kokoro: Print test output to stdout

Give build_info.py the executable bit

Fix recently found non-determinism with gl_WorldToObject3x4EXT.

CMake: Move project() to top of CMakeLists.txt

Add bison license to LICENSE.txt

This problem needs to be fixed, but in parallel, we need to see master
and any other changes to it passing all tests.

The removed test is ray-tracing centric, and may indicate non-determinism
in recent code added for that functionality.

Also remove `NOTICE` from message() about PCHs - it seems to print this in the actual message, contrary to the documentation where it is used as a severity.

Revert "Merge pull request #2330 from ShabbyX/optimize_for_angle"

This reverts commit 1ee5d1c0, reversing
changes made to 906d48a7.

Add missing comma from license-checker.cfg

Fixes license checker presubmit.

Common: include standard headers before doing any defines

currently, due to

```c++
\#if (defined(_MSC_VER) && _MSC_VER < 1900 /*vs2015*/) || defined MINGW_HAS_SECURE_API
    #include <basetsd.h>
    #ifndef snprintf
    #define snprintf sprintf_s
    #endif
    #define safe_vsprintf(buf,max,format,args) vsnprintf_s((buf), (max), (max), (format), (args))
```

defining `snprintf` to `sprintf_s` essentially unconditionally, this will break the
stdio.h+cstdio system header for mingw-w64 g++ in msys2 with shaderc
https://github.com/google/shaderc/issues/1065

an alternative change would be
https://raw.githubusercontent.com/shinchiro/mpv-winbuild-cmake/master/packages/glslang-0001-fix-gcc-10.1-error.patch
in which the `|| defined MINGW_HAS_SECURE_API` part is removed
Signed-off-by: Christopher Degawa <ccom@randomderp.com>

Optimize for angle

Fix CMake rules when nesting CMake projects

`${CMAKE_SOURCE_DIR}` points to the outer project root, not the current directory.

Fixes building of `glslang` when included into another CMake project.

Attempt to fix chromium builds

It would seem that `glslang_sources` has a private dependency on `glslang_build_info`, so `glslang_validator` cannot transitively `#include` the generated `glslang/build_info.h` header.

Add `glslang_build_info` as a direct dependency to `glslang_validator`.
Also remove the duplicate dependency on `glslang_build_info` in `glslang_sources_common`

Note: This is a speculative fix as I can build Chromium fine without these changes.
Not sure what's different between these configs.

Generate build information from CHANGES.md

This PR significantly reworks the way glslang is versioned.

Instead of committing changes to the `GLSLANG_MINOR_VERSION` define in
`glslang/Public/ShaderLang.h`, and using `make-revision` to generate
`GLSLANG_PATCH_LEVEL` in `glslang/Include/revision.h`, all version
information is now derived from the new `CHANGES.md` file.

`CHANGES.md` acts as the single source of truth for glslang version
information, along with a convenient place to put all release notes for
each notable change made.

`CHANGES.md` is parsed using the new `build_info.py` python script.
This script can read basic template files to produce new source files,
which it does to read the new `build_info.h.tmpl` to generate (at build
time) a glslang private header at
`<build-dir>/include/glslang/build_info.h`.
I've written generators for each of the CMake, Bazel, gn, and
`Android.mk` build scripts.

The new version code conforms to the Semantic Versioning 2.0 spec.

This new version is also used by the CMake rules to produce versioned
shared objects, including a major-versioned SONAME.

New APIs:
---------

* `glslang::GetVersion()` returns a `Version` struct with the version
  major, minor, patch and flavor.

Breaking API changes:
---------------------

* The public defines `GLSLANG_MINOR_VERSION` and `GLSLANG_PATCH_LEVEL`
  have been entirely removed.
* `glslang/Public/ShaderLang.h` and `glslang/Include/revision.h` have
  been deleted.
* Instead, `<build-dir>/include/glslang/build_info.h` is created in
  the build directory, and `<build-dir>/include` is a CMake `PUBLIC`
  (dependee-inherited) include directory for the glslang targets.
* `<build-dir>/include/glslang/build_info.h` contains the following
   new #defines:
   `GLSLANG_VERSION_MAJOR`, `GLSLANG_VERSION_MINOR`,
   `GLSLANG_VERSION_PATCH`, `GLSLANG_VERSION_FLAVOR`,
   `GLSLANG_VERSION_GREATER_THAN(major, minor, patch)`,
   `GLSLANG_VERSION_GREATER_OR_EQUAL_TO(major, minor, patch)`,
   `GLSLANG_VERSION_LESS_THAN(major, minor, patch)`,
   `GLSLANG_VERSION_LESS_OR_EQUAL_TO(major, minor, patch)`
*  The CMake install output directory contains a copy of
   `build_info.h` at: `include/glslang/build_info.h`
*  Python3 is now always required to build glslang (likely always
   required for transitive dependency builds).