Except for OpConstant and OpSpecConstant, all other literal number
operands are indeed unsigned integers. So,
* Rename all *LITERAL_NUMBER* operand types to *LITERAL_INTEGER*.
* Expect unsigned integers for *LITERAL_INTEGER* operands.
* Keep MULITPLE_WORD_LITERAL untouched since it is only used by
OpConstant and OpSpecConstant.
And we want to provide the capability to specify floating-point
numbers after !<integer> in the alternate parsing mode. So,
OPTIONAL_LITERAL_NUMBER is reserved for OPTIONAL_CIV.
Affects OpConstant, and OpSwitch.
Adds constant libspirv::kUnknownType for readability.
Adds tests for hexadecimal number parsing.
Updates syntax.md to describe hex parsing, including
sign extension.
Move the definition of spv_instruction_t to an internal
header file, since it now depends on C++ and is not
used by the external interface.
Use a std::vector<uint32_t> in spv_instruction_t
instead of a fixed size array.
