[clang] [Clang][AArch64] Add ACLE macros to support Armv9.6 (PR #176755)

[Alexis Engelke via cfe-commits]

aengelke wrote:

This doesn't seem to be just measurement noise to me, though: when looking at [the table](https://llvm-compile-time-tracker.com/?config=Overview&stat=instructions%3Au&branch=origin%2Fmain&startHash=1d316ef4ba71d843f1e49f86e831dbf8c64ebd83) around commit [c97d0bc17a](https://github.com/llvm/llvm-project/commit/c97d0bc17a7677f4022a345fc4adae09198e3952) (which is this PR), there is a bump by 20-30M instrs. for aarch64 right at this commit and this seems to be much larger than the typical noise in other unrelated commits, which is around +/-5M instrs.

https://github.com/llvm/llvm-project/pull/176755