Mark overriden Tensor method `override` (#47198)

Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/47198

Fixes:

```xplat/caffe2/aten/src/ATen/native/xnnpack/OpContext.h:77:10: error: 'run' overrides a member function but is not marked 'override' [-Werror,-Winconsistent-missing-override]
  Tensor run(const Tensor& input);```

Test Plan: CI tests

Reviewed By: kimishpatel

Differential Revision: D24678573

fbshipit-source-id: 244769cc36d3c1126973a67441aa2d06d2b83b9c
diff --git a/aten/src/ATen/native/xnnpack/OpContext.h b/aten/src/ATen/native/xnnpack/OpContext.h
index e696ad3..a3902da 100644
--- a/aten/src/ATen/native/xnnpack/OpContext.h
+++ b/aten/src/ATen/native/xnnpack/OpContext.h
@@ -70,7 +70,7 @@
     output_max_ = max;
   }
 
-  Tensor run(const Tensor& input);
+  Tensor run(const Tensor& input) override;
 
   static c10::intrusive_ptr<LinearOpContext> create_context(
       Tensor&& weight,