Update template specialization to reflect API changes.

po_iterator_storage's insertEdge was updated to reflect the API
changes from many of our insert methods in r222334, however the
template specialization for external storage was not updated. This
updates the specialization.

llvm-svn: 222446

llvm/include/llvm/ADT/PostOrderIterator.h

@@ -76,8 +76,9 @@ public:
   // Return true if edge destination should be visited, called with From = 0 for
   // the root node.
   // Graph edges can be pruned by specializing this function.
-  template<class NodeType>
-  bool insertEdge(NodeType *From, NodeType *To) { return Visited.insert(To); }
+  template <class NodeType> bool insertEdge(NodeType *From, NodeType *To) {
+    return Visited.insert(To).second;
+  }
 
   // Called after all children of BB have been visited.
   template<class NodeType>