[lld] [LLD][ELF][AArch64] Add BTI Aware long branch thunks (PR #108989)

[Fangrui Song via llvm-commits]

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@@ -2257,6 +2257,16 @@ std::pair<Thunk *, bool> ThunkCreator::getThunk(InputSection *isec,
   return std::make_pair(t, true);
 }
 
+std::pair<Thunk *, bool> ThunkCreator::getSyntheticLandingPad(Defined &d,
+                                                              int64_t a) {
+  auto res = landingPadsBySectionAndAddend.try_emplace(
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MaskRay wrote:

Could use `auto [it, isNew]` to improve clarity

https://github.com/llvm/llvm-project/pull/108989