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

[Wenzel Jakob via llvm-commits]

wjakob wrote:

Thank you @lhames, please let me know if I can help with anything.

This specific fix aside, I am also wondering if we discuss (perhaps in a separate issue) a way to link into a flat buffer that has better long-term stability as the currently broken API is also on the way out. (You mentioned the following two potential paths that sound like they would work)

>  I'm wondering if we could get by with a "SectionMerger" plugin that merges all blocks into a single section with RWX permissions

> Alternatively we could expose an API that allows you to merge simple LinkGraphs directly into a flat buffer, then we expose the existing SectCreate utility that allows you to add buffers directly to the JIT with a given set of permissions and associated symbols. (This wouldn't let you control its final load address though)

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