refactor: use const reference for parents in CTxMemPool::UpdateAncestorsOf

src/txmempool.cpp

@@ -276,7 +276,7 @@ bool CTxMemPool::CalculateMemPoolAncestors(const CTxMemPoolEntry &entry,
 
 void CTxMemPool::UpdateAncestorsOf(bool add, txiter it, setEntries &setAncestors)
 {
-    CTxMemPoolEntry::Parents parents = it->GetMemPoolParents();
+    const CTxMemPoolEntry::Parents& parents = it->GetMemPoolParentsConst();
     // add or remove this tx as a child of each parent
     for (const CTxMemPoolEntry& parent : parents) {
         UpdateChild(mapTx.iterator_to(parent), it, add);