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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202953 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/IPO/MergeFunctions.cpp

@@ -561,7 +561,7 @@ public:
     initializeMergeFunctionsPass(*PassRegistry::getPassRegistry());
   }
 
-  bool runOnModule(Module &M);
+  bool runOnModule(Module &M) override;
 
 private:
   typedef DenseSet<ComparableFunction> FnSetType;