[C++11] Add 'override' keyword to virtual methods that override their base class.

llvm-svn: 203999

clang/lib/StaticAnalyzer/Checkers/SimpleStreamChecker.cpp

@@ -99,7 +99,7 @@ public:
   StopTrackingCallback(ProgramStateRef st) : state(st) {}
   ProgramStateRef getState() const { return state; }
 
-  bool VisitSymbol(SymbolRef sym) {
+  bool VisitSymbol(SymbolRef sym) override {
     state = state->remove<StreamMap>(sym);
     return true;
   }