This PR only changes a few lines of code, but is subtle.

In HLSL, comparison operators (<,>,<=,>=,==,!=) operate component-wise
when given a vector operand.  If a whole vector equality or inequality is
desired, then all() or any() can be used on the resulting bool vector.

This PR enables this change.  Existing shape conversion is used when
one of the two arguments is a vector and one is a scalar.

Some existing HLSL tests had assumed == and != meant vector-wise
instead of component-wise comparisons.  These tests have been changed
to add an explicit any() or all() to the test source.  This verifably
does not change the final SPIR-V binary relative to the old behavior
for == and !=.  The AST does change for the (now explicit, formerly
implicit) any() and all().  Also, a few tests changes where they
previously had the return type wrong, e.g, from a vec < vec comparison
in hlsl.shapeConv.frag.

Promotion of comparison opcodes to vector forms
(EOpEqual->EOpVectorEqual) is handled in promoteBinary(), as is setting
the proper vector type of the result.

EOpVectorEqual and EOpVectorNotEqual are now accepted as either
aggregate or binary nodes, similar to how the other operators are
handled.  Partial support already existed for this: it has been
fleshed out in the printing functions in intermOut.cpp.

There is an existing defect around shape conversion with 1-vectors, but
that is orthogonal to this PR and not addressed by it.

Disabled MSVC 2015 compile warnings.

HLSL: fix defect in EOpMethodSampleCmp* texture decomposition

HLSL: phase 4 of RWTexture support: add image atomics

HLSL: Fix unary and binary operator type conversion issues

SPV: Add missing guard to code that uses AMD extensions

HLSL holds the compare value in a separate intrinsic arg, but the AST wants
a vector including the cmp val, except in the 4-dim coord case, where it
doesn't fit and is in fact a separate AST parameter.  This is awkward but
necessary, given AST semantics.  In the process, a new vector is constructed
for the combined result, but this vector was not being given the correct
TType, so was causing some downstream troubles.

Now it is.  A similar defect existed in OpTextureBias, and has also been
fixed.

A need arose to use capabilities from TIntermediate during
node promotion.  These methods have been moved from virtual
methods on the TIntermUnary and TIntermBinary nodes to methods
on TIntermediate, so it is easy for them construct new nodes
and so on.

This is done as a separate commit to verify that no test results
are changed as a result.

This PR will turn Interlocked* intrinsics using rwtexture or rwbuffer
object as the first parameter into the proper OpImageAtomic* operations.

Otherwise compilation fails when ENABLED_AMD_EXTENSIONS is off.

This fixes defects as follows:

1. handleLvalue could be called on a non-L-value, and it shouldn't be.

2. HLSL allows unary negation on non-bool values.  TUnaryOperator::promote
   can now promote other types (e.g, int, float) to bool for this op.

3. HLSL allows binary logical operations (&&, ||) on arbitrary types, similar
   (2).

4. HLSL allows mod operation on arbitrary types, which will be promoted.
   E.g, int % float -> float % float.

VS2010 compile fixes

HLSL: phase 3 of rwtexture support: add sub-vec4 capabilities

Use pthread_mutex for global lock on Linux.

SPV: Add missing extension declarations for certain AMD extensions.

HLSL: allow multi-dimensional arrays

This uses the Unknown storage format, instead of deducing the
format from the texture declaration type.

Also makes a (correct) test change for global -> temp vars.

This PR sets the TQualifier layoutFormat according to the HLSL image type.
For instance:

  RWTexture1D <float2> g_tTex1df2;

becomes ElfRg32f.  Similar on Buffers, e.g, Buffer<float4> mybuffer;

The return type for image and buffer loads is now taken from the storage format.
Also, the qualifier for the return type is now (properly) a temp, not a global.

HLSL: phase 2: add operator[]

Check for out-of-range bindings during IO mapping.

All the underpinnings are there; this just parses multiple array dimensions
and passes them through to the existing mechanisms.

Also, minor comment fixes, and add a new test for multi-dim arrays.

* This avoids an internal compile error on VS2010 possibly related to
  std::enable_if use.