[lld/mac] Port typo correction for undefined symbols from ELF port

Ports:
- core feature: https://reviews.llvm.org/D67039
- case mismatch: https://reviews.llvm.org/D70506
- extern "C" suggestions: https://reviews.llvm.org/D69592,
  https://reviews.llvm.org/D69650

Does not port https://reviews.llvm.org/D71735 since I believe that that doesn't
apply to lld/Mach-O.

Differential Revision: https://reviews.llvm.org/D135038