Fix build error: [FPEnv][EarlyCSE] Support for CSE when exception behavior is...

Fix build error: [FPEnv][EarlyCSE] Support for CSE when exception behavior is "ignore" or "maytrap" and the rounding mode is known.

This should fix these build bot errors:

Step 6 (build-check-mlir-build-only) failure: build (failure)
C:\buildbot\mlir-x64-windows-ninja\llvm-project\llvm\lib\Transforms\Scalar\EarlyCSE.cpp(124): error C2220: the following warning is treated as an error
C:\buildbot\mlir-x64-windows-ninja\llvm-project\llvm\lib\Transforms\Scalar\EarlyCSE.cpp(124): warning C4996: 'llvm::Optional<llvm::fp::ExceptionBehavior>::getValue': Use value instead.
C:\buildbot\mlir-x64-windows-ninja\llvm-project\llvm\lib\Transforms\Scalar\EarlyCSE.cpp(129): warning C4996: 'llvm::Optional<llvm::RoundingMode>::getValue': Use value instead.
C:\buildbot\mlir-x64-windows-ninja\llvm-project\llvm\lib\Transforms\Scalar\EarlyCSE.cpp(1386): warning C4996: 'llvm::Optional<llvm::fp::ExceptionBehavior>::getValue': Use value instead.
C:\buildbot\mlir-x64-windows-ninja\llvm-project\llvm\lib\Transforms\Scalar\EarlyCSE.cpp(1388): warning C4996: 'llvm::Optional<llvm::RoundingMode>::getValue': Use value instead.