Put quote marks around strings, due to a change in how tokenization works.

Remove execute permissions

tooling: Fix update sources script for Python 3

Fixed a typo leading to compilation error.

Fix build.

Also use the glslang namespace qualifier consistently and validate after
legalization, not before. (But most tests don't legalize.)

SPV: Add SPIRV-Tools validator.

This one small change allows the update_glslang_sources.py script to operate correctly with Python 2 and Python 3.

Change the string literal type to "bytes" so that it matches the type returned by the subprocess calls.  Otherwise, under Python 3, the search for "known-good" in the list of remotes always fails.  This is OK for the first execution of update_glsang_sources, since the remote is not there on the first run.  But on subsequent runs, the search still fails to match and the script stops when trying to create a remote that already exists.

Use our own SPIRV-Tools message stringifier

Stop including an internal SPIRV-Tools header. It has been
deleted.

Fixes #1477

SPV: only declare the pure 8/16-bit capabilities when needed.

Update SPIRV-Tools known good.

Includes:

    Update OpPhi instructions after splitting block. (#1783)
    Don't change decorations and names in merge return. (#1777)
    Transform to combine consecutive access chains
    Handle undef literal value in vector shuffle
    Fix block ordering in dead branch elim
    Fix finding constant with particular type. (#1724)
    Fix infinite loop while folding OpVectorShuffle (#1722)
    Fix size error when folding vector shuffle. (#1721)
    Layout validation: Permit {vec3; float} tight packing

Only when operations stray outside the 8/16-bit storage-capabilities
are the general (pure 8/16-bit) capabilities needed.

Order is kept about the same.

Fix -Wignored-qualifier and -Wunused-variable warnings

Appveyor CI: build artifacts for x64

Fixes https://github.com/KhronosGroup/glslang/issues/1396

Non-Functional: Add postprocess as more robust way to add capabilities

When capabilities are needed for specific SPIR-V instructions, it is
fragile to do so based on GLSL/AST usage; it should be based on actual
instructions they got translated to.