[llvm] [aarch64] Mix the frame pointer with the stack cookie when protecting the stack (PR #161114)

[Eli Friedman via llvm-commits]

https://github.com/efriedma-quic approved this pull request.

LGTM.

I'll wait a couple days to merge in case anyone else wants to comment.  Ping me if I forget.

https://github.com/llvm/llvm-project/pull/161114