[llvm] OrcV2: also set COFF flag overrides when custom linking layer is used (PR #129533)

[Wenzel Jakob via llvm-commits]

wjakob wrote:

Dear @lhames,

I was wondering what I could do to get this unblocked. Current LLVM builds crash with my project when used on Windows because of this issue. Does this current commit still crash in the MLIR test suite after I reverted the latest change?

https://github.com/llvm/llvm-project/pull/129533