Nonfunctional: Remove declaration for ShGetPhysicalAttributeBindings

The function ShGetPhysicalAttributeBindings() is declared in the
header, but not defined (or referenced) anywhere in the codebase.

Reflection: Add support for querying vertex attributes in reflection API

Parser: Redeclaration of gl_CullDistance is disallowed mistakenly.

Testing: Add link tests in the GTest framework

SPV: Fix missing location decoration for structures put directly on input/output interfaces

Spec for decorating the OpVariable:
	"The remaining variables listed by OpEntryPoint with the Input or Output storage class form the user-defined variable interface. These variables must be identified with a Location decoration"

Spec for decorating struct type:
	"The layout of a structure type used as an Input or Output depends on whether it is also a Block (i.e. has a Block decoration).
	If it is a not a Block, then the structure type must have a Location decoration"

Merge branch 'struct_member_decorations' of https://github.com/scyganINTEL/glslang into scyganINTEL-struct_member_decorations

SPV: Correct an issue in createUnaryMatrixOperation().

Type of the source is not necessarily the same as that of the destination.

VS2010 compilation fixes

These capabalities were added on declaration of the members, but
that is considered too aggressive, as those members are automatically
declared in some shaders that don't use them.  Now, actual access
is needed to make the capabalities be declared.

Tests: Add support for testing file-based HLSL source code in GTest.

SPV: Handle matrix's OpFConvert vector by vector.

Parser: Add missing vector relational functions for double type.

Build: Minor android compile warning fix

* Fixes a warning - static function being defined but not used.
* Just in case any more code is added to DetachThreadLinux, this will go
  through the same path on both platforms.

Build: fix for -Werror=non-virtual-dtor for Android system builds

Parser: Redeclare gl_ClipDistance/gl_CullDistance should update their array sizes.

SPV: Add capability ImageGatherExtended if necessary.