[lld] [lld][MachO] Respect dylibs linked with `-allowable_client` (PR #114638)

[Carlo Cabrera via llvm-commits]

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carlocab wrote:

Not sure what the policy is on binary test files, but it seems to be needed for now while `ld64.lld` doesn't know how to use `-allowable_client`.

I could also implement that here, but I wanted to keep the diff as small as possible. Happy to implement that in a follow-up and remove this test binary.

https://github.com/llvm/llvm-project/pull/114638