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

[Jonathan Thackray via cfe-commits]

jthackray wrote:

Linux and Windows builds are passing, but someone has left a trailing whitespace character at clang/docs/ReleaseNotes.rst:407 (not me), so I'll merge anyway.

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