[lld] [llvm] [lld][MachO] Follow-up to use madvise() for threaded file page-in. (PR #157917)

[Daniel Rodríguez Troitiño via llvm-commits]

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

This PR doesn't change the tests to not be `UNSUPPORTED` everywhere: https://github.com/llvm/llvm-project/blob/c98e867822d8e741159ff0be09ccc2a5c7841a28/lld/test/MachO/read-workers.s#L2-L4

This is not being tested at all in CI. Should that be changed?

https://github.com/llvm/llvm-project/pull/157917