Adds --hlsl-iomap option to perform IO mapping in HLSL register space.

--shift-cbuffer-binding is now a synonym for --shift-ubo-binding.

The idea way to do this seems to be passing in a dedicated IO resolver, but
that would require more intrusive restructuring, so maybe best for its
own PR.

The TDefaultHlslIoResolver class and the former TDefaultIoResolver class
share quite a bit of mechanism in a common base class.

TODO: tbuffers are landing in the wrong register class, which needs some
investigation.  They're either wrong upstream, or the detection in the
resolver is wrong.

Also, fixed one test file that didn't have its syntax error as the last line.

Longer term, this storage class should be generated based on the mode
of compilation.

HLSL: structuredbuffer counter functionality

This adds TProgram::getUniformBlockCounterIndex(int index), which returns the
index the block of the counter buffer associated with the block of the passed in
index, if any, or -1 if none.

This is WIP, heavy on the IP part.  There's not yet enough to use in real workloads.

Currently present:

* Creation of separate counter buffers for structured buffer types needing them.
* IncrementCounter / DecrementCounter methods
* Postprocess to remove unused counter buffers from linkage
* Associated counter buffers are given @count suffix (invalid as a user identifier)

Not yet present:

* reflection queries to obtain bindings for counter buffers
* Append/Consume buffers
* Ability to use SB references passed as fn parameters

HLSL: Fix #672: Support 1.#INF and -1.#INF syntax.

Null-conversion needs the right sized vectors to kick out with matching types.

HLSL: fix return type for isfinite

The prior decomposition of isfinite was not setting the return type on the
sequence node.  (Sequence was used because there's an internal temporary
to avoid the complex rvalue problem).

Implement the extension SPV_KHR_16bit_storage

HLSL: cast bracket dereference index to int type if not.

HLSL can index arrays using operator[] with non-integer types, and
inserts a conversion to a uint if needed.

HLSL: allow non-vec3 tessellation coordinate declarations

Corresponds to the EShMsgHlslOffsets flag in messages.
Works for both GLSL and HLSL.

HLSL requires vec2 tessellation coordinate declarations in some cases
(e.g, isoline topology), where SPIR-V requires the TessCoord qualified
builtin to be a vec3 in all cases.  This alters the IO form of the
variable to be a vec3, which will be copied to the shader's declared
type if needed.  This is not a validation; the shader type must be correct.

C++11 features remove the dependencies from OS specific code. Changes:

- Making WorkList class to have its own mutex instead of the OS specific
global one. The new mutex is the one from std library. The OS specific
code is also removed.

- Using the C++11 std library to handle threads in StandAlone
application
and enabling concurrent processing on non-windows platforms.

- converting the global variable Worklist into local variable workList.

Somewhat complex due to recognizing a general scalar, but not
replicating it for each member to avoid side effects.

HLSL: Decompose OpIsFinite to avoid capability restrictions