[StaticAnalysis] Remove unnecessary parameter in CallGraphNode::addCallee.

[hokein]

Summary

Remove the CallGraph in addCallee as it is not used in addCallee.
It decouples addCallee from CallGraph, so that we can use CallGraphNode
within our customized CallGraph.

include/clang/Analysis/CallGraph.h

public:
   inline iterator begin() { return CalledFunctions.begin(); }
   inline iterator end()   { return CalledFunctions.end(); }
   inline const_iterator begin() const { return CalledFunctions.begin(); }
   inline const_iterator end()   const { return CalledFunctions.end();   }
 
   inline bool empty() const {return CalledFunctions.empty(); }
   inline unsigned size() const {return CalledFunctions.size(); }
 
-  void addCallee(CallGraphNode *N, CallGraph *CG) {
+  void addCallee(CallGraphNode *N) {
     CalledFunctions.push_back(N);
   }
 
   Decl *getDecl() const { return FD; }
 
   void print(raw_ostream &os) const;
   void dump() const;
 };

lib/Analysis/CallGraph.cpp

Decl *getDeclFromCall(CallExpr *CE) {
     }
 
     return nullptr;
   }
 
   void addCalledDecl(Decl *D) {
     if (G->includeInGraph(D)) {
       CallGraphNode *CalleeNode = G->getOrInsertNode(D);
-      CallerNode->addCallee(CalleeNode, G);
+      CallerNode->addCallee(CalleeNode);
     }
   }
 
   void VisitCallExpr(CallExpr *CE) {
     if (Decl *D = getDeclFromCall(CE))
       addCalledDecl(D);
   }
 
CallGraphNode *CallGraph::getOrInsertNode(Decl *F) {
 
   std::unique_ptr<CallGraphNode> &Node = FunctionMap[F];
   if (Node)
     return Node.get();
 
   Node = llvm::make_unique<CallGraphNode>(F);
   // Make Root node a parent of all functions to make sure all are reachable.
   if (F)
-    Root->addCallee(Node.get(), this);
+    Root->addCallee(Node.get());
   return Node.get();
 }
 
 void CallGraph::print(raw_ostream &OS) const {
   OS << " --- Call graph Dump --- \n";
 
   // We are going to print the graph in reverse post order, partially, to make
   // sure the output is deterministic.