CallGraph: Add getNode() method, constify.

llvm-svn: 152439
diff --git a/clang/lib/Analysis/CallGraph.cpp b/clang/lib/Analysis/CallGraph.cpp
index ca73c4a..cc6e62c 100644
--- a/clang/lib/Analysis/CallGraph.cpp
+++ b/clang/lib/Analysis/CallGraph.cpp
@@ -136,6 +136,10 @@
   }
 }
 
+CallGraphNode *CallGraph::getNode(const Decl *F) const {
+  return FunctionMap.find(F)->second;
+}
+
 CallGraphNode *CallGraph::getOrInsertFunction(Decl *F) {
   CallGraphNode *&Node = FunctionMap[F];
   if (Node)