rm ste::move when return a unique_ptr in inference

paddle/contrib/inference/paddle_inference_api_impl.cc

@@ -141,7 +141,7 @@ std::unique_ptr<PaddlePredictor> PaddlePredictorImpl::Clone() {
     return nullptr;
   }
   // fix manylinux compile error.
-  return std::move(cls);
+  return cls;
 }
 
 // TODO(panyx0718): Consider merge with Init()?