Basic (component) type conversion was done, but checking that the composite
was correct was not being done.

Fixes issue #353.

This is to make the real change needed in the next commit easier.

Symbol table sharing has different sets of symbols for different
versions. This needs to take into account that SPIR-V has different
symbols than non-SPIR-V.

HLSL: Add lerp, fix sincos ret, add ret type tests, non-square mats, tx semantics

Front-end: allow max size built-in arrays like gl_ClipDistance

Fixed off-by-one error with gl_MaxClipDistances and similar limits.

Add HLSL memory barrier intrinsics, fix dst, add lit & EvaluateAttrib…

This lets ES shaders use non-constant initializers for non-constant globals.

SPV doesn't allow gaps in the components of the texturing coordinate.
It also removes the shadow reference.
So, close up the components so all used components are together.

A barrier (ESSL/GLSL) or OpControlBarrier when in a tessellation control
shader also means doing memory synchronization for output variables.

HLSL: Implement atomic ops, bit conversions, fix minor intrinsics bugs

Build: Tracking allocator must use const key

Fixes TMap template.

This is required to build with newer libc++ versions that have a static
assert on const-ness of value_type

HLSL: Add decompositions for some intrinsics.

Build: Compilation fix (mingw64)

Details within these bear even more fleshing out, but would like to have
that driven by actual need.

SPV: Fix pointer address spaces for sampler function parameters

For opaque types such as samplers, images, and atomic counters, we want to
reference the actual object in the child function.  For a long time, we
used a shadow variable and made a copy of the image/sampler.  In 76d0ac1a,
this was changed to not shadow samplers.  However, this didn't cover all
opaque types and it also didn't get the pointer storage classes right.
This commit fixes both of these issues.

Fixes #324

SPV: Defer capability decl for ClipDistance, CullDistance, PointSize until…

The compiler will mark struct members with those builtins, but won't
declare the capability until that member is accessed by some executable
instruction.

Test changes:
- spv.430.vert: was missing ClipDistance capability.
- spv.precise.tese: remove TessellationPointSize capability.

Build: Fix Ubuntu 16.10 build