1. The test cases of OpReadClockKHR is invalid. The return type is
unsigned integer rather than signed integer.
2. When SPIR-V decorate or SPIR-V type is specified, we should avoid
auto location mapping because the semantics are totally decided by
SPIR-V tokens.
- Add support of SPIR-V execution mode qualifiers.
- Add support of SPIR-V storage class qualifier.
- Add support of SPIR-V decorate qualifiers.
- Add support of SPIR-V type specifier.
- Add support of SPIR-V intruction qualifiers.
- Add support of spirv_by_reference/spirv_literal parameter qualifier.
- Add shader stage macros introduced by this extension.