Allow GL_NV_mesh_shader in fragment shaders for perprimitiveNV

- Emit relevant capability/extension for use of perprimitiveNV in fragment shader
- Remove redundant checks for mesh shader qualifiers in glslang.y
- Add profile version check for use of extension GL_NV_mesh_shader
- Add a new gtest for use of perprimitiveNV in fragment shader

Fixup unused parameter warnings

This CL removes the current parameters which are unused in order to
fixup the issued clang warnings.

BUILD.gn: remove the static_library target.

This had no sources and depended on a source_set which is an invalid use
of GN because the source_set gets propagated to dependents of the
static_library instead.

Fix a parse issue of imageAtomicCompSwap()

The max count of arguments is 5 when image2DMS/image2DMSArray is
specified.

Fix flags.nonprivate to be true for workgroup memory, which is implicitly workgroupcoherent/nonprivate

Fix flags.nonprivate to be true for workgroup memory, which is implicitly workgroupcoherent/nonprivate

Allow redeclaration of builtin interface blocks in mesh shader

Fix inferred output primitive for GL_NV_geometry_shader_passthrough 

For GL_NV_geometry_shader_passthrough extension, the Inferred output primitive for ElgTriangles should be ElgTriangleStrip.

Also removed unnecessary relax for GL_NV_geometry_shader_passthrough in link validate

Enhancement: add extra command line options that modifies aml

Apart from allowing redeclaration of gl_MeshPerVertexNV and gl_MeshPerPrimitiveNV blocks, this change also -
- Resize clip/cull perview distances based on static index use
- Error out use of both single-view and per-view builtins
- Add new gtests with redeclared blocks and edit existing test output
- Fix couple of typos

BUILD.gn: glslang_sources need the public config too

BUILD.gn: only use complete_static_lib on mac

This will be used to generate uniform locations with --aml

Add ES 320 support and additional error checks for SPV_NV_mesh_shader

Also continue error checking post requireStage() check

BUILD.gn: make the static_lib complete to fix the build on OSX

This also fixes some cpp files that uncover issues when building
with the flags turned off.

Remove NV_EXTENSION ifdefs from ShaderLang.h

This allows library consumers to work without have to set
NV_EXTENSIONS.

Fix missing case label for miss stage.

Add BUILD.gn configuration.

- Add ES 320 support
- Error out use of perprimitiveNV for non mesh/fragment shaders
- Error out use of mesh/task shaders w/o use of NV_mesh_shader
- Error out use of NV_mesh_shader for non task/mesh shaders
- Error out use of perviewNV for non mesh shaders
- Error out use of taskNV for non mesh/task shaders
- Add test case for mesh shader with ES 320 profile