Don't output duplicate OpTypeAccelerationStructureNV declarations

GL_EXT_buffer_reference

* Make sure source strings are terminated

The source strings may or may not have a null terminator. We need to
make sure we add one before outputting the source strings as we iterate
over the c-str looking for the null terminator.

* Review feedback

Mark spv.int16.amd.frag.out as failing validation

See #1642

Also updates SPIRV-Tools and SPIRV-Headers known_good.

Create separate OpSource for each included file when compiling -g

Add passes to spirv-opt passes to preserve source line info when compiling -g.

CMake: Fix linking pthread of CMake < 3.1

As reported in #1624, Ubuntu 14.04 LTS still uses CMake 2.8.12 which
does not support the Threads::Threads target (added in CMake 3.1).

This could be reverted once the required CMake version is bumped to 3.1+.

Move memory model scope tests to Vulkan 1.1 batch

Fixes #1610

* Updated expected result due to version change

Fixes #1630 and fixes #1631.

Fix bug where shaderRecordNV buffers were using StorageBuffer storage class

From internal Khronos discussions, work, and testing.

Update to newest SPIRV-Tools, emit default Binding decoration.

Update to newest SPIRV-Tools. It checks the Vulkan rule that all resources must have a set and binding decoration, which many tests fail. So add code to set a default value of zero. Also disable PCH for Ninja builds.

Add to README: git config --global core.fileMode false

Remove Unix executable permission from text files

CMake: Link OSDependent with Threads::Threads

Would typically be pthreads.
Without this, '-Wl,--no-undefined' would output these errors:

/usr/bin/ld: OSDependent/Unix/libOSDependent.a(ossource.cpp.o): in function `glslang::OS_CleanupThreadData()':
/home/akien/Mageia/Sandbox/_rpm/BUILD/glslang-7.10.2984/glslang/OSDependent/Unix/ossource.cpp:83: undefined reference to `__pthread_register_cancel'
/usr/bin/ld: /home/akien/Mageia/Sandbox/_rpm/BUILD/glslang-7.10.2984/glslang/OSDependent/Unix/ossource.cpp:93: undefined reference to `__pthread_unregister_cancel'
/usr/bin/ld: OSDependent/Unix/libOSDependent.a(ossource.cpp.o): in function `glslang::OS_AllocTLSIndex()':
/home/akien/Mageia/Sandbox/_rpm/BUILD/glslang-7.10.2984/glslang/OSDependent/Unix/ossource.cpp:122: undefined reference to `pthread_key_create'
/usr/bin/ld: OSDependent/Unix/libOSDependent.a(ossource.cpp.o): in function `glslang::OS_SetTLSValue(void*, void*)':
/home/akien/Mageia/Sandbox/_rpm/BUILD/glslang-7.10.2984/glslang/OSDependent/Unix/ossource.cpp:137: undefined reference to `pthread_setspecific'
/usr/bin/ld: OSDependent/Unix/libOSDependent.a(ossource.cpp.o): in function `glslang::OS_FreeTLSIndex(void*)':
/home/akien/Mageia/Sandbox/_rpm/BUILD/glslang-7.10.2984/glslang/OSDependent/Unix/ossource.cpp:162: undefined reference to `pthread_key_delete'
/usr/bin/ld: OSDependent/Unix/libOSDependent.a(ossource.cpp.o): in function `glslang::InitGlobalLock()':
/home/akien/Mageia/Sandbox/_rpm/BUILD/glslang-7.10.2984/glslang/OSDependent/Unix/ossource.cpp:175: undefined reference to `pthread_mutexattr_init'
/usr/bin/ld: /home/akien/Mageia/Sandbox/_rpm/BUILD/glslang-7.10.2984/glslang/OSDependent/Unix/ossource.cpp:176: undefined reference to `pthread_mutexattr_settype'
/usr/bin/ld: OSDependent/Unix/libOSDependent.a(ossource.cpp.o): in function `glslang::OS_GetTLSValue(void*)':
/home/akien/Mageia/Sandbox/_rpm/BUILD/glslang-7.10.2984/glslang/OSDependent/Unix/ossource.cpp:149: undefined reference to `pthread_getspecific'

SPIR-V OpLines now contain filenames from HLSL-style #lines.

Update test infrastructure

* Changed unit tests to only record known the validation pass/fail
status
 * errors are output as part of the failure message if the result is
 unexpected
 * can turn off validation for each test individually
* Moved some SPV_KHR_vulkan_memory_model tests to be compiled for Vulkan
1.1

Rename GL_KHX_shader_explicit_arithmetic_types to GL_EXT_shader_expli…

GlslangToSpv: prevent add XfbStride twice

Without this commit, if the XfbStride was explicitly set, the
decoration was added twice on the shader.

v2 (changes after Jonh Kessenich first review)
   * Simplified by just removing the firs assignment
   * Removed assert

SPV: Generate OpArrayLength with no signedness.