[libunwind] [libunwind][AArch64] Disable ZA before resuming from unwinding (on Linux) (PR #165451)

[Sander de Smalen via cfe-commits]

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@@ -827,6 +827,53 @@ DEFINE_LIBUNWIND_FUNCTION(__unw_getcontext)
   ret
 #endif
 
+//
+// extern "C" bool __libunwind_Registers_arm64_za_disable()
+//
+// On return:
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sdesmalen-arm wrote:

It's unclear from the name or this description what the intent of this function is, but it seems this is trying to reimplement `__arm_za_disable`. Can you add a comment describing what this function does?

https://github.com/llvm/llvm-project/pull/165451