[clang] [LifetimeSafety] Add multi-block support to buildOriginFlowChain (PR #204592)

[via cfe-commits]

================
@@ -275,6 +274,35 @@ class AnalysisImpl
     return LoanSetFactory.getEmptySet();
   }
 
+  BuildOriginFlowChainResult
----------------
NeKon69 wrote:

```suggestion
  std::pair<llvm::SmallVector<OriginID>, bool>
```

No need to add a new type.

https://github.com/llvm/llvm-project/pull/204592