[clang] [llvm] [AArch64][clang] Fix `__arm_atomic_store_with_stshh` ordering and lowering (PR #191301)

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

If the CPU itself can do illegal reordering, then add a fence, sure, but if it's just the compiler, we should be able to fix the intrinsic?

https://github.com/llvm/llvm-project/pull/191301