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

[Lang Hames via llvm-commits]

lhames wrote:

> In my case I don't think I really need to interact with JITLink besides turning it on (if not already on by default on Windows) and persisting/loading .so files representing individual compiled functions to a cache. The API surface is small (https://github.com/mitsuba-renderer/drjit-core/commit/8c5ec998eaeb10c4eaae9890a3a4a7c782d7b9ed).

Ok. Side note though: JITLink loads `.o` files (i.e. relocatable objects) rather than shared objects. You could use `.so` files and `dlopen` instead, but `JITLink` is probably the right target in your case: it saves you a link step, and can enable direct calls between objects (where they're allocated close together in memory), which dynamic libraries can't generally do.

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