HLSL: fix crash on empty struct return from entry point

This allows global initializers to use $Global members.

Thanks to @steve-lunarg for his input and discussions on handling member functions.

Another precurser to getting member non-static functions working.

HLSL: use prefix for builtin functions names to avoid namespace colli…

HLSL: Buffer types should be unsampled.

It would have been possible for globally scoped user functions to collide
with builtin method names.  This adds a prefix to avoid polluting the
namespace.

Ideally this would be an invalid character to use in user identifiers, but
as that requires changing the scanner, for the moment it's an unlikely yet
valid prefix.

Still need: pass by reference in SPIR-V and symbol-table level
for accessing 'this' members from member functions.

Also use this to move deferred member-function-body parsing to a better
place.

This should also be well poised for implementing the 'namespace' keyword.

RWBuffer objects were generating (properly) unsampled resoures, while
Buffer objects were not.  This fixes that.

Adding a test for this also uncovered an extraneous \r in the runtests script,
fixed now.

SPV: Fix unexpected declarations of capability and extension

Fix building on MinGW-w64

Merge branch 'semantic_handling' of https://github.com/TiemoJung/glslang into TiemoJung-semantic_handling

Makes some white-space differences in most output, plus a few cases
where more could have been put out but was cut short by the previous
fix-sized buffer.

These were recently added for all profiles, versus just desktop.

HLSL: Additional channel value for textureGatherXXX().

When mapping HLSL gather intrinsics to GLSL textureGatherXXX() built-in
function, the channel selection value is only valid for non-shadow samplers.

Some HLSL to Spirv tests fail.

This is needed for accessing types/variables within a member function body that are
not known until after the struct is finished being declared. However, that funtionality
is not yet present, this is just the deferred processing, which is working for
static member functions.

Added 'GL_core_profile' and 'GL_compatibility_profile' to macro expansion

Added version check (version >= 150) for GL_(core/compatibility)_profile macros.

Added GL_core_profile standard macro check to "150.vert" test file.

Fixed version check for GL_core_profile macros, and removed bad token character from 150.vert test.

Updated 150.vert.out test base-result with google-test suite.