Fixes #1572

This is totally optional, but lets people build this repo with
ccache to improve rebuild speeds.  It also can help a great deal
on ccache-enabled CI systems like Travis-CI.  We build fixed
revisions of glslang a lot on Travis, so this will be a big help
with CI machine loading.

Allowed for LIB_TYPE to be set to switch between static and shared libs for glslang, SPIRV, and HLSL

Cmake now looks for External/spirv-tools. If found, it links in
SPIRV-Tools-opt and SPVRemapper, and adds -DENABLE_OPT to build.

Remapper errors are generally fatal: there has been some unexpected situation while
parsing the SPV binary, and there is no reasonable way to carry on.  The
errorHandler() function is called in this case, which by default exits, but
it is possible to submit a handler which does not.  In that case the remapper would
carry on in a bad state.

This change ensures a graceful termination of the remap() function.

While a try {} catch {} construct would be the ideal and safe way to do this,
that's off limits for certain environments, so this tries to do the same thing
with explicit code, to catch all the bailout paths.

As a static target, when included in other cmake projects, it is not needed to install these libraries and headers as part of this build, and just need to link to this.

This reverts commit cfc69d95.
* Change CMAKE_INSTALL_PREFIX default on Windows in order
  to prevent permission denied errors when trying to install
  to "Program Files".

* Use `GNUInstallDirs` in order to respect GNU conventions.
  This is especially important for multi-arch/multi-lib setups.
* Specify position independent mode building properly, without
  using the historic hack of adding `-fPIC` as a definition.
  This makes the build system more portable.
* Only detect C++ (and not C) to slightly speed up configuring.
* Specify C++11 mode using modern CMake idioms.
* Fix some whitespace issues.

Some HLSL to Spirv tests fail.

Matches existing options.

bump required CMake version down to 2.8.11 since no features are required in cmake>2.8.11 and this allows building on stock CentOS 7

- Support GL_AMD_shader_ballot (SPV_AMD_shader_ballot).
- Support GL_AMD_shader_trinary_minmax (SPV_AMD_shader_trinary_minmax).
- Support GL_AMD_shader_explicit_vertex_parameter
  (SPV_AMD_shader_explicit_vertex_parameter).
- Support GL_AMD_gcn_shader (SPV_AMD_gcn_shader).

Avoids the need to ship basic runtimes like libgcc_s_sjlj-1.dll
with the executables.

This adds solution folders that properly group gtest/glslang/hlsl.
This also marks gtest options as advanced so they don't show up
in cmake-gui by default.

CMake 2.8.12 added support for target_include_directories(), among
other features, and we would like to use it.

The existing test harness is a homemade shell script. All the tests
and the expected results are written in plain text files. The harness
just reads in a test, invoke the glslangValidator binary on it, and
compare the result with the golden file. All tests are kinda
integration tests.

This patch add Google Test as an external project, which provides a
new harness for reading shader source files, compile to SPIR-V, and
then compare with the expected output.

Dealing with the 110 toolset seems not worth it.

* Linux folder has been renamed to Unix, to match defines and so that it
  compiles on OS X.
* This removes the need for a per-platform include search path for the
  right OS folder

Stop forcing CMAKE_INSTALL_PREFIX="install". If the user manually set
CMAKE_INSTALL_PREFIX, then trust that he knows what he's doing.

This patch does NOT change the project's default value ("install") of
CMAKE_INSTALL_PREFIX.

Change-Id: I81b46dd1986427b498fe6316bed03f01689987d4

glslang build: force the use of -std=c++11 when building with Clang.  David Neto <dneto@google.com>.

git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@31583 e7fa87d3-cd2b-0410-9028-fcbf551c1848

git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@31180 e7fa87d3-cd2b-0410-9028-fcbf551c1848