[clang] [clang] Update Mach-O ptrauth driver defaults (PR #132834)

[Francis Visoiu Mistrih via cfe-commits]

francisvm wrote:

> Looks like @ahmedbougacha might be out. @francisvm, could you take a look?

@rjmccall / @jroelofs might be able to help!

https://github.com/llvm/llvm-project/pull/132834