[clang] [llvm] Add support for Arm Cortex A78AE CPU (PR #84485)

[Jonathan Thackray via cfe-commits]

jthackray wrote:

> Should this be added to the release notes? (so it doesn't get forgotten in a mad scramble in a few months time)

Sure, happy to do that.

https://github.com/llvm/llvm-project/pull/84485