linkValidate: Round up structure sizes to vec4 in std140

The argument version is passed in from above and struct handling ensures
that row-majorness gets propagated correctly from one level to the next.
If we just look at the type itself and it's embedded in a struct that's
declared row-major, we may get the wrong stride.

SPV: Handle stride decorations for arrays of arrays, and using multiple type instances when strides are used.

Before, it was only including explicit interface, sufficient for IO-Block-declared
oriented interface, but not sufficient for all modes GLSL might be used with
SPIR-V.

Two things are accomplished now:
1) each id will appear exactly once
2) the OpEntryPoint list will union static use with declarations

This includes doing structure uniqueness modulo majorness, for shared nested structures.

This also distinguishes between the same struct included in multiple parent packings.

SPV: Fix an issue related with imageStore() for 2DMS.

Parser: Correct the storage qualifier of gl_HelperInvocation.

SPV: Implement GLSL built-in bitcast functions.

Display the filename if we have output, even if validating  a single file

This also made the function easier to read by identifying
left and right operands more clearly.

Fix compile warning/error due to assignment in while() loop

This causes build failures with -Werror=parentheses

An extra line of error recovery code set a non-sense combination of
es version and core profile.

'invocations' was using 0 as the "shader never set" flag and as the
default. Formalize this and explicit set to 1 and link time.

To do this, more generally use a named -1 as a not set value.

SPV: Smear should use type of the scalar to make the expected vector type when the provided vector type is incompatible with the scalar.