script: Improve update sources script

- remove unused variable to pass pylint
- Use another approach to detect if known-good remote is already
  present to avoid the need for "ignore following errors" message.

Build: Make literal casting have fewer warnings and be more consistent.

Add support for OpConstantNull and OpConstantSampler to spirv-remap

Fixes issue #1408

This reverts commit ebec9094.

Khronos decided glslang was originally correct, and the specifications
are incorrect.

Take into account arrays of opaque types with --auto-map-bindings

TDefaultIoResolverBase::reserveSlot and getFreeSlot now have a size
parameter to reserve a range of bindings. This is used by
TDefaultIoResolver::resolveBinding to reserve a continuous range when
the type is an array and the target API is GL.

Update spirv-tools known-good

Includes the following spirv-opt improvements:

Preserve inst-to-block and def-use in passes.
Add store for var initializer in inlining.
Handle types with self references.

Relax a stringToDouble test for, OSX AppleClang 9.1

1e-323 was flushed to zero.
1e-308 is also flushed to zero.
Use 1e-307 instead, which still satisfies the test intent.

Fixes #1400

The major version number was bumped in the previous commit to support
this.

Fix several signed/unsigned comparison compile warnings.

Update spirv-tools known-good.

Includes:

Fold FMix feeding Extract, and use the simplification pass.

CMake: use target_include_directories to expose includes

This makes glslang simpler to embed in larger projects.

Fix TextureUpgradeAndSamplerRemovalTransform when used with qualifiers

Add bit width of types to disassembleInstruction

PP: Fix strtod problems: add tests, remove 2nd use, replace

Fixes #1228. Fixes #234.

This uses imbue() to be locale independent.  Notes:

- 'sstream >> double' is much slower than strtod()
  * this was measurable in the test suite as a whole, despite being
    a tiny fraction of what the test suite does
- so, this embeds a fast path that bypasses sstream most of the time
  => the test suite is faster than before
- sstream is probably slower, because it does more accurate rounding than strtod()
- sstream does not create INFINITY by itself, this was done based on failure inferencing

This partly addresses #1228 and #234 by reducing usage of strtod (or atof).
There is now only place to parse a floating-point number.

- Adds a pragma to see binary output of double values (not portable)
- Print decimals that show more values, but in a portable way
  (lots of portability issues)
- Expand the tests to test more double values

Note: it is quite difficult to have 100% portable tests for floating point.
The current situation works by not printing full precision, and working around
several portability issues.

Update spirv-tools known-good

Includes:

Fold divide and multiply by same value.
Allow ADCE to remove more instructions.
Remove dead Workgroup variables in ADCE.
Fold fclamp feeding compare.
Add pass to fold a load feeding an extract.
Remove redundant stores.
SROA: Only create symbols that are loaded.
Get ADCE to handle OpCopyMemory
Remove the limit on struct size in SROA.

The transform removes sampler arguments from functions and function
calls; this causes function arguments to change their indices. When some
function arguments have an output qualifier, this qualifier can get lost
because of the removal which can lead to incorrect results (e.g. out
qualifier not having effect).

To fix this we iterate through both seq & qual arrays in lock-step and
manually remove/replace entries as appropriate.

HLSL: allow self-type cast (as no-op passthrough)

Previously, casting an object of a struct type to an identical type
would produce an error.  This PR allows this case.

As a side-effect of the change, several self-type casts in existing
tests go away.  For example:

    0:10          Construct float ( temp float)
    0:10            'f' ( in float)

becomes this (without the unneeded constructor op):

    0:10          'f' ( in float)

For vector or array types this can result in somewhat less overall code.

Fixes: #1218