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

[Wenzel Jakob via llvm-commits]

wjakob wrote:

> What customizations are you using? Do you need to control layout, or just find out where particular sections / symbols are?

I need to control the layout. I am using `LLVMOrcCreateRTDyldObjectLinkingLayerWithMCJITMemoryManagerLikeCallbacks` to place generated code into a flat buffer that can contains everything (code, data). Only %rip-relative accesses. An application can later map this data into memory and run it without using any of the LLVM infrastructure.

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