Fix unintended casting to long

Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/12341

Reviewed By: ezyang

Differential Revision: D10205876

fbshipit-source-id: b0678b019b196ac9ee52969f80819ee9ee442bf2
diff --git a/caffe2/operators/stats_put_ops.h b/caffe2/operators/stats_put_ops.h
index 659df21..cf41bb5 100644
--- a/caffe2/operators/stats_put_ops.h
+++ b/caffe2/operators/stats_put_ops.h
@@ -47,7 +47,7 @@
 
  private:
   const std::string given_name_;
-  const long magnitude_expand_;
+  const int64_t magnitude_expand_;
   T stat_;
 };
 } // namespace caffe2