[lld] [lld-macho] Omit `__llvm_addrsig` metadata from the output (PR #98913)

[Daniel Bertalan via llvm-commits]

BertalanD wrote:

Thank you for checking!

I would prefer merging this as-is, as `removeRefsToErasedIsecs` would otherwise be dead code until your PR is merged. It won't be too much work to add it back if it turns out necessary.

(I'm a bit skeptical about it: does the swift runtime expect that the pointers with the erased relocs might be null? What does ld do?)

Sidenote: I tried looking into what the `_constg_swiftt` could be about. Didn't get far, because enabling category merging and relative method lists crashes LLD. Will file a bug about it.

https://github.com/llvm/llvm-project/pull/98913