[libunwind] [libunwind] Fix exposure of UNW_AARCH64_RA_SIGN_STATE through _Unwind… (PR #205188)

[Daniil Kovalev via cfe-commits]

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+// -*- C++ -*-
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kovdan01 wrote:

Very minor nit: BTW, which C++ features does this test rely on, except a couple of `constexpr` named constants? It's just looks very C-style, and I'm wondering if it would make sense to make it actually C source, not C++.

Feel free to ignore

https://github.com/llvm/llvm-project/pull/205188