CLOn12 compiler follow-ons
Follow-ons from !7565 (merged):
-
Clover changes to enable building without native IR support for AMD, including dropping the need for libelf -
Clover changes to enable building with MSVC so I can verify later refactorings with LLVMPipe -
Refactoring Clover's Clang invocation to a shared location so we can share with the CLOn12 compiler -
Refactoring CLOn12's and Clover's SPIR-V argument parsing to be handled by vtn instead -
Fix saturating conversions from float32 -> int64/uint64