[llvm] [AArch64][SME] Handle SME state around Darwin TLS-descriptor calls (PR #216017)

[Sander de Smalen via llvm-commits]

https://github.com/sdesmalen-arm approved this pull request.

This looks sensible to me. However, it seems like we're still missing similar behaviour for functions with `__arm_agnostic("sme_za_state")` (not specific to Darwin).

https://github.com/llvm/llvm-project/pull/216017