[llvm] [MachineOutliner][NFC] Refactor (PR #105398)

[Ellis Hoag via llvm-commits]

================
@@ -684,7 +688,7 @@ void MachineOutliner::findCandidates(
       continue;
     }
 
-    FunctionList.push_back(*OF);
+    FunctionList.push_back(std::make_unique<OutlinedFunction>(*OF));
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ellishg wrote:

Does this work?
```suggestion
    FunctionList.emplace_back(*OF);
```

https://github.com/llvm/llvm-project/pull/105398