Adding missing anchor to DATDeltaAlgorithm.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146025 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/ADT/DAGDeltaAlgorithm.h

@@ -36,6 +36,7 @@ namespace llvm {
 /// for more information on the properties which the predicate function itself
 /// should satisfy.
 class DAGDeltaAlgorithm {
+  virtual void anchor();
 public:
   typedef unsigned change_ty;
   typedef std::pair<change_ty, change_ty> edge_ty;