The grammar for no semicolon and no object name for cbuffer/tbuffer
was correct, but the production still skipped the anonymous declarations
if an identifier followed.

This is to create more stable test results.

This allow for propagation through structs with dynamically indexed
arrays. This supports recent removal of non-io struct flattening.

Set type to r-value resulting from indexing vector, to prevent
float->uint conversion when source is already uint. Resulting
OpConvertFToU would otherwise fail validation because source is
already uint.
For LoadN, incorrect uint->float->uint can be avoided; fixing
potential truncation of big integer values.

The memory model group agreed to these definitions for how
to map GLSL barrier, memoryBarrier, etc. With HLSL following suit.

Also, only emit this XFB information where the SPIR-V spec says
it should be emitted: essentially, on objects.

This and the previous commit together fix #1185.

This implementation uses the GLSL extension
GL_NV_conservative_raster_underestimation to generate the new SPIR-V
FullyCoveredEXT built in.

Some stage (e.g, hull shaders) have arrayed builtin outputs (e.g, position).
When copying from the internal structure to the split form, it is necessary
to propagate that indirection to the actual arrayed outputs.  This was not
happening.

Addresses #1181

Fixes #979

This makes struct returns from functions work, but breaks
structs containing arrays, due to limitations in subsequent
transforms in spirv-opt. This is expected to be fixed soon.

Adds command line options:

   --invert-y
   --iy

(synonyms) which invert position.Y on vertex shader output.  Handles these cases:

* Direct single variable return
* Member of direct returned struct
* Single variable output parameter
* Member of struct output parameter

API:

    // Enables position.Y output negation in vertex shader
    void TShader::setInvertY(bool invert);

Fixes #1173

This continues to prevent writing output buffers (out from a function),
but fixes the problem where the copy-in/out was not getting done.

Making everything work will require knowing both in/out-ness and bufferness,
but these are currently mutually exclusive, because both are storage
qualifiers.

Minor change to add a compilation warning on implicit matrix size
truncations.

(This is motivated by wanting to retickle the tests.)

Issue #791 was partially fixed by PR #1161 (the mat mul implicit
truncations were its main point), but it still wouldn't compile due to
the use of ConstantBuffer as an identifier.  Apparently those fall into
the same class as "float float", where float is both a type and an
identifier.

This allows struct definitions with such keyword-identifiers,
and adds ConstantBuffer to the set.  'cbuffer int' is legal in HLSL,
and 'struct int' appears to only be rejected due to the redefinition
of the 'int' type.

Fixes #791

Goes with PR #1161, and completes the space for mul() implicit truncations.

Note that the v*v and scalar cases are already handled by existing code.

HLSL truncates the vector, or one of the two matrix dimensions if there is a
dimensional mismatch in m*v, v*m, or m*m.

This PR adds that ability.  Conversion constructors are added as required.

Fixes #1158.
Fixes #1159.

If a shader includes a mixture of several stages, such as HS and GS,
the non-stage output geometry should be ignored, lest it conflict
with the stage output.

This is currently parsed and ignored, save for some minor validation.

Almost equivalent to tbuffer, except members not at global scope.
So, reference is "TextureBuffer_var.member", not simply "member".

Both debug and release clang builds have segfaulted on recent
changes, non deterministically, while doing the single/multi-thread
test all test files. Removing recent test files, to see if it gives
a clue.