spirv: Add no-op support for VK_GOOGLE_hlsl_functionality1

spirv: Add no-op support for VK_GOOGLE_hlsl_functionality1

This extension adds two new decorations which carry meaning only for
HLSL shaders.  They are expected to be handled by higher level layers
and can be ignored by implementations.  However, it does save the client
a bit of work if the implementation safely ignores them instead of the
client having to strip them out of the SPIR-V in order for it to be
valid.

Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>