[compiler-rt] [compiler-rt][AArch64] Rewrite SME routines to all use __aarch64_cpu_features. (PR #119414)

[Jon Roelofs via llvm-commits]

jroelofs wrote:

I'm not sure we want this on Darwin and maybe Fuchsia platforms, since it would require calling `__init_cpu_features_resolver` to initialize `__aarch64_cpu_features`. On some platforms that happens automatically via an `__attribute__((constructor))` function, but Darwin and Fuchsia don't, and instead rely on an FMV resolver triggering it.

cc @aemerson

https://github.com/llvm/llvm-project/pull/119414