Also bump version for recent changes.

ParseHelper: assign global XfbBuffer to a block missing it

Implement GL_EXT_fragment_invocation_density

Add conversion folding when the source is a constant.

Update known good SPIRV tools and headers

* Fixes use of optimizer
* Updated test outputs
 * GeometryStreams and TransformFeedback no longer fail validation

including SPV generation using SPV_EXT_fragment_invocation_density.
This is an alias of the functionality in SPV_NV_shading_rate, and thus in some
cases we can only have one set of the tokens present (switch statements), so
we have picked the EXT version. This required updating the expected test
results for SPV_NV_shading_rate.

Also updated the known-good for spirv-headers so that the validator in
spirv-tools knows about the new extension.

This change adds unary conversion folding when the source is a constant.
This fixes an ISV issue whereby:

```
const float16_t f = float16_t(42.0);
```

Wouldn't compile because the conversion operator would always produce an
EvqTemporary when it could have produced an EvqConst.

I've also added a test case that proves out that all basic-type to
basic-type conversions work.

GLSL: Fix #1591: Require the id in subgroupBroadcast to be constant.

Update to newer SPIRV-Tools, including VK_EXT_scalar_block_layout

Validator has more refined messages about what kind of block layout
rules have been applied.

Merge branch 'scalar_block_layout' of https://github.com/jeffbolznv/glslang into jeffbolznv-scalar_block_layout

[HLSL/Spir-V] fix for incorrect spir-v on int dot(int, int)

Decomposes OpDot into corresponding multiplies and additions.

HLSL: implemented c register handling

HLSL: fix invalid spir-v vector * scalar for float1

Updated type conversion rules for HLSL frontend

Missing check for float results in always emitting OpIMul even for float types

Adjusted a test not to use c register for
a structured buffer, they are supposed to
use t registers

Added comments with hints for what are the
register types are used for.

Handle potentially uninitialized result

PCH filename depends on current binary dir

Fixes #1572

Fix parser issue: redeclare gl_FragStencilRefARB is not supported

If a block has assigned a XfbOffset it is assumed that it would
inherit the current global XfbBuffer. This commit fixes two use cases:

1) Getting the members of a Block with a XfbOffset to be assigned an
   offset, as explained on GLSL 4.60 spec, section "4.4.2 Output
   Layout Qualifiers", subsection "Transform Feedback Layout
   Qualifiers".

2) Compute properly an error on overlapping ranges if a block is
   assigned a XfbOffset and one of it members is assigned a explicit
   one. This gets working because when the members of a block get
   assigned a Offset/Buffer at fixBlockXfbOffsets, then the block is
   deassigned the Offsets, so ranges are computed only with the block
   members.

BTW, this is already done when redeclaring block builtins.

Fixes #1535

Apinheiro/xfb struct assignment

Add DeadBranchElim before MergeReturn in legalization.

MergeReturn now requires this or could throw an error.