apply clang-tidy modernize-use-override

Summary: Use clang-tidy to mechanically add missing `override` and remove redundant `virtual`.

Reviewed By: igorsugak

Differential Revision: D5211868

fbshipit-source-id: 15cec17d39690ffa8072ffeccdf9fedaae1f6839
diff --git a/caffe2/contrib/warpctc/ctc_op.h b/caffe2/contrib/warpctc/ctc_op.h
index 2feb7ab..1a1bcac 100644
--- a/caffe2/contrib/warpctc/ctc_op.h
+++ b/caffe2/contrib/warpctc/ctc_op.h
@@ -37,7 +37,7 @@
   CTCOp(const OperatorDef& operator_def, Workspace* ws)
       : Operator<Context>(operator_def, ws) {}
 
-  bool RunOnDevice() {
+  bool RunOnDevice() override {
     // inputs
     const auto& inputs = Input(INPUTS);
     const auto minibatchSize = inputs.dim(1);
diff --git a/caffe2/core/net.h b/caffe2/core/net.h
index 78d7ec3..81b934c 100644
--- a/caffe2/core/net.h
+++ b/caffe2/core/net.h
@@ -147,7 +147,7 @@
  public:
   using ExecutionChains = std::unordered_map<int, std::vector<int>>;
   DAGNetBase(const NetDef& net_def, Workspace* ws);
-  ~DAGNetBase();
+  ~DAGNetBase() override;
   bool Run() override;
   // WorkerFunction() is a function wrapper to allow us to run worker threads.
   // It checks out one ready-to-run operator from the job queue, runs it,