[lld] [lld][ELF] Extend profile guided function ordering to ELF binaries (PR #117514)

[Fangrui Song via llvm-commits]

https://github.com/MaskRay requested changes to this pull request.

I need time to look at the ELF port changes.

If you drop ELF changes from this PR, and just move MachO code to Common to be reused, this PR will be good to go and I'll approve.

You need a dependent ELF patch.

https://github.com/llvm/llvm-project/pull/117514