Preserve signedness in SPIR-V image query ops

The AST->SPIRV translation of image queries was dropping signedness,
causing some validation troubles.

HLSL: preserve empty structures after splitting

Compile fixes for VS2010

HLSL: Enable GatherCmpRed.  Green/Blue/Alpha cannot be supported.

* Removed range-based for
* Added explicit return type to non-trivial lambda
* Added explicit scope for tInterstageIoData

This implements GatherCmpRed in terms of OpImageDrefGather.

There appears to be no way to implement the Green/Blue/Apha forms: see #673.

This (and previous commit) is a better foundation to build real methods on.

HLSL: Non-functional: Don't process function name/parameters before expected a function declaration.

HLSL: use LOD form of ImageQuerySize when needed.

This is slightly cleaner today for entry-point wrapping, which sometimes made
two subtrees for a function definition instead of just one subtree.  It will be
critical though for recognizing a struct with multiple member functions.

The non-LOD form of image size query is prohibited in certain cases:
see the OpImageQuerySize and OpImageQuerySizeLod sections of the SPIR-V
spec for details.  Sometimes we were generating the non-LOD form when
we should have been using the LOD form.  Sometimes the LOD form is required
even if the underlying HLSL query did not supply a MIP level itself,
in which case level 0 is now queried.

HLSL: Fix ordering defect if global SB decl after fn param

This change propagates the storage qualifier from the buffer object to its contained
array type so that isStructBufferType() realizes it is one.  That propagation was
happening before only for global variable declarations, so compilation defects would
result if the use of a function parameter happened before a global declaration.

This fixes that case, whether or not there ever is a global declaration, and
regardless of the relative order.

This changes the hlsl.structbuffer.fn.frag test to exercise the alternate order.

There are no differences to generated SPIR-V for the cases which successfully compiled before.

Rename KHX_multiview/device_group to EXT_multiview/device to match the released specs

GL_KHX_multiview and GL_KHX_device_group don't exist,
they were released as GL_EXT_multiview and GL_EXT_device_group.

More build fixes

Fix another build warning on some platforms

Use an explicit cast from size_t to int to avoid warning.

Sanitize ShaderLang.h

Fix build warnings on some platforms

Use an explicit cast from size_t to int to avoid errors like the following:
glslang\glslang\MachineIndependent\preprocessor\Pp.cpp(1053) : error C2220: warning treated as error - no 'object' file generated
glslang\glslang\MachineIndependent\preprocessor\Pp.cpp(1053) : warning C4267: '=' : conversion from 'size_t' to 'int', possible loss of data

affects Pp.cpp, hlslParseHelper.cpp.

Initialize local variable to get rid of warningsa about potentially
uninitialized variables:
glslang\hlsl\hlslparsehelper.cpp(3667) : error C2220: warning treated as error - no 'object' file generated
glslang\hlsl\hlslparsehelper.cpp(3667) : warning C4701: potentially uninitialized local variable 'builtIn' used

affects hlslParseHelper.cpp

ShaderLang.h contains declaration for `ShLink` function which is never
defined.

See this grep output:

$grep -Hrn 'ShLink'
glslang/Public/ShaderLang.h:206:SH_IMPORT_EXPORT int ShLink(
glslang/Public/ShaderLang.h:214:SH_IMPORT_EXPORT int ShLinkExt(
glslang/MachineIndependent/ShaderLang.cpp:1268:int ShLinkExt(

HLSL: small fix for index type in f16tof32 opcode

The f16tof32 opcode was indexing a vector with a float 0, rather
than an int 0.  It may have made no functional difference due to the
identical bit pattern, but code looking at the type could be
confused.

HLSL: add structuredbuffer pass by reference in fn params