Add no-unused-but-set-parameter to skip verbose warning

[Menooker]

I received the following warning messages many times while compiling. g++ version 9.4.0

/home/shared/bin/mlir/20240505/include/mlir/IR/Attributes.h: In instantiation of ‘static bool llvm::CastInfo<To, From, typename std::enable_if<(is_same_v<mlir::Attribute, typename std::remove_const<From>::type> || is_base_of_v<mlir::Attribute, From>), void>::type>::isPossible(mlir::Attribute) [with To = mlir::Attribute; From = mlir::Attribute]’:
/home/shared/bin/mlir/20240505/include/llvm/Support/Casting.h:311:29:   required from ‘static To llvm::DefaultDoCastIfPossible<To, From, Derived>::doCastIfPossible(From) [with To = mlir::Attribute; From = mlir::Attribute; Derived = llvm::CastInfo<mlir::Attribute, mlir::Attribute, void>]’
/home/shared/bin/mlir/20240505/include/llvm/Support/Casting.h:657:46:   required from ‘decltype(auto) llvm::dyn_cast(From&) [with To = mlir::Attribute; From = mlir::Attribute]’
/home/shared/bin/mlir/20240505/include/mlir/IR/OpImplementation.h:972:38:   required from ‘mlir::ParseResult mlir::AsmParser::parseAttribute(AttrType&, mlir::Type, llvm::StringRef, mlir::NamedAttrList&) [with AttrType = mlir::Attribute]’
/home/shared/bin/mlir/20240505/include/mlir/IR/OpImplementation.h:948:58:   required from here
/home/shared/bin/mlir/20240505/include/mlir/IR/Attributes.h:417:49: warning: parameter ‘ty’ set but not used [-Wunused-but-set-parameter]
  417 |   static inline bool isPossible(mlir::Attribute ty) {

This PR disables the warnings for non-MSVC builds.

[kurapov-peter]

@Menooker, is it for MLIR build? If so, I'd suggest we set the flag for the target only and use stricter rules for our code.

[Menooker]

@Menooker, is it for MLIR build? If so, I'd suggest we set the flag for the target only and use stricter rules for our code.

Yes, it is for MLIR only. I have updated the code to let the CXX flag only affect on MLIR targets only.

[Menooker]

The lines are copied from MLIR upstream. They have the same issue too.