The program demonstrates basic shader compilation using the Shaderc
C++ API.  For clarity, each method is deliberately self-contained.

Techniques demonstrated:
- Preprocessing GLSL source text
- Compiling a shader to SPIR-V assembly text
- Compliing a shader to a SPIR-V binary module
- Setting basic options: setting a preprocessor symbol.
- Checking compilation status and extracting an error message.

This lets us keep better track of licenses for our dependencies.

Class shaderc::CompilationResult is a template over the element type for
the compilation output. It has three specializations: for a SPIR-V
binary module (with uint32_t element type), SPIR-V assembly text (char
element type), and preprocessed source (char element type).

The compilation output is accessed via cbegin(), cend() and begin()
end() iterators.

Test code updates:
- Add 'using' declarations for all three compilation result
  classes.
- Add const to compilation result variables, where possible.
- IsValidSpv should take an SpvCompilationResult, and should not
  be parameterized over compilation result types.
- IsValidSpv should take an SpvCompilationResult
- Test PreprocessingOnlyOption should use a
  PreprocessedSourceCompilationResult variable instead of an
  AssemblyCompilationResult variable.

Remove SetDisassemblyMode and SetPreprocessOnlyMode methods on the
CompileOptions object so we can't get the wrong output by mixing up
options with compilation methods.

Removed FileCompiler members disassemble_ and preprocess_only_

Remove Disassembly and PreprocessOnly options on shaderc_util::Compiler

C API changes:

- Use different compile functions in the C API for different output types.
- Remove disassembly mode and preprocess-only mode calls.

The build-version target depends on glslang and spirv-tools
so we have to make sure they are included before generating the
custom target.

When glslang_tab.cpp and glslang_tab.cpp.h moved, the include directory
was not updated.

This was missed because the old files had not been removed from the
source directory.

Only overwrite if new content is different.
Record date for unknown hashes.

Also bump the newly inserted copyright messages to 2016.

That README describes how to link to libshaderc, as well
as what to put on your search path.

Clients of the libshaderc API should add
$SHADERC_SRC_ROOT/libshaderc/include to their search path, and
use #include "shaderc/shaderc.hpp" or "shaderc/shaderc.c"

Update the include guards for shaderc.h and shaderc.hpp

Rename the result object from shaderc_spv_module to
shaderc_compilation_result. Also rename the involved methods, variables,
and handlers.

Rename an enum status: shaderc_compilation_status_null_result_module to
shaderc_compilation_status_null_result_object.

This allows both spirv-tools and glslang to live in separate source
directories when being invoked with ndk-build.

ndk-build THIRD_PARTY_PATH=foo  specifies that foo/glslang and
foo/spirv-tools exist.

ndk-build SPVTOOLS_LOCAL_PATH=/some/absolute/path specifies that glslang
exists in third_party/glslang but spirv-tools exists at
/some/absolute/path.

ndk-build GLSLANG_LOCAL_PATH=/some/absolute/path is the same but for
glslang.

This cleans up a number of warnings related to glslang_tab.cpp.
It also allows the generation of libshaderc_combined by calling
ndk-build libshaderc_combined.

Change the output data container of libshaderc compilation result from
std::string to std::vector<uint32_t> to guarantee the output data alignment.

Change the libshaderc_util::Compiler::Compile() signature and
implementation to avoid extra copies of SPIR-V binary. Also store the
string data of text output in vector<uint32_t>.

Instead use shaderc_module_get_status and check for return value
shaderc_compilation_status_success.

Addresses https://github.com/google/shaderc/issues/129

Makefile.

get the output file name for compilation result.

Change the contained data type of libshaderc_util::Compiler::predefined_macros_ from libshaderc_util::string_piece to std::string

Adjust tests to include an appropriate #version string.

Also, when testing disassembled output, only test certain key substrings
so we're not so sensitive to code generation differences in Glslang.

add another checking class for glslc which only expect a specified substring appearing in the whole error message, use this class for target-env glslc test

spirv-tools will add this test itself.

shaderc_combined.lib will now be built and tested when compiling
for MSVC or Ninja on Windows.

Replaces the .in file with a constructed set of generator expressions.

This avoids issues with echo behaving differently on different systems.

It specifies the target environment, determining
available language features, and builtin, and SPIR-V
conventions.

Note that the -std determines the dialect of the shader
source code.  That's subtly different.

It just looks better.

We only Initialize/Finalize process every compile because there
is a subset of options that interfere with internal glslang
state. Until this is remedied in glslang, allow re-use of
state except in the cases where we know state will get broken.

If a third-party project defines a CMake function with the same
name, by importing that project's CMake configuration, we may end
up overwriting our own copy. Qualify all defined functions to
reduce that probability.