[libunwind] [llvm] [MC][AArch64] Add .cfi_llvm_set_ra_sign_state for PAuth_LR (PR #205442)

[Jon Roelofs via cfe-commits]

================
@@ -7282,6 +7283,8 @@ bool AArch64AsmParser::ParseDirective(AsmToken DirectiveID) {
     parseDirectiveCFINegateRAState();
   else if (IDVal == ".cfi_negate_ra_state_with_pc")
     parseDirectiveCFINegateRAStateWithPC();
+  else if (IDVal == ".cfi_llvm_set_ra_state")
----------------
jroelofs wrote:

I don't have strong feelings on whether this should be `.cfi_set_ra_state` vs `.cfi_llvm_set_ra_state`, but given there doesn't yet appear to be a binutils implementation of this cfi, I'm trying to be respectful of the top-level namespace. @walkerd @MaskRay any opinion here?

https://github.com/llvm/llvm-project/pull/205442