Implement the extension GL_AMD_texture_gather_bias_lod

Setting component=0 is later taken to mean the shader did so, which
is not always legal. It should instead set the component as not set
by the shader.

This implements a recent change to the GLSL specification to enforce
this ill-defined situation.

Remove empty cpp files

HLSL: add test coverage for sub-vec4 texture intrinsics

SPV: When passing structs of opaque types, flatten and pass the membe…

For "s.m = t", a sampler member assigned a sampler, make t an alias
for s.m, and when s.m is flattened, it will flatten to the alias t.
Normally, assignments to samplers are disallowed.

This avoids either A) needing uniformConstant struct, or
B) initializing a struct with opaque members, as writing them is not
allowed.

Because it is valid in HLSL to alias bindings:
A) remove validation that aliasing is not done
B) make the algorithms tolerate aliasing

This changes no functional code.  There was a bit of a testing hole
in that textures templatized on sub-vec4 types were not being exercised
with any intrinsics.  This adds some basic sanity coverage of that case.

HLSL: Add an Includer to handle #include for local HLSL paths.

Parser: Add missing codes for float16

SPV: Add OpSource shader source code and file name.

Note that declaratives are not handled, only procedurals.

Pure Texture to Sampled Texture Transform

Adds a transformation step to the post processing step.
Two modes are available:
1) keep
- Keeps samplers, textures and sampled textures as is
2) transform pure texture into sampled texture and remove pure samplers
- removes all pure samplers
- transforms all pure textures into its sampled counter part

Change-Id: If54972e8052961db66c23f4b7e719d363cf6edbd

HLSL: Add imat, umat, and bmat constructors

Fixes #894

Blocks have this on members, not the object.

HLSL: allow name mangling based on texture template type

This was done for one direction, but not both directions, so this commit
picks up the other direction.

This seems a bit ill-defined, and was generating code that made OpPhi of two
operands that were Boolean vectors result in a scalar bool.

Name mangling did not account for the vector size in the template type of a texture.
This adds that.  The mangle is as it ever was for the vec4 case, which leaves
all GLSL behavior and most HLSL behavior uneffected.  For vec1-3 the size is added
to the mangle.

Current limitation: textures cannot presently be templatized on structured types,
so this works only for vectors of basic types.

Fixes #895.

This solves ranlib warnings on MacOS.

SPV: Give error on not assigning locations to I/O when generating SPIR-V.

Remapper: handle embedded opcode in OpSpecConstantOp

OpSpecConstantOp contains an embedded opcode which is given as a literal
argument to the OpSpecConstantOp.  The subsequent arguments are as the
embedded op would expect, which may be a mixture of IDs and literals.  This
adds support for that to the remapper binary parser.  Upon seeing such an
embedded op, the parser flips over to parsing the argument list as
appropriate for that opcode.

Fixes #882.

Also, provides an option to auto-assign locations.
Existing tests use this option, to avoid the error message,
however, it is not fully implemented yet.

HLSL: add ability to pass struct buffers with counters to fns