chore: import upstream snapshot with attribution

paddle/phi/kernels/sequence_pool_kernel.h

@@ -0,0 +1,26 @@
+/* Copyright (c) 2023 PaddlePaddle Authors. All Rights Reserved.
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License. */
+
+#pragma once
+
+#include "paddle/phi/core/dense_tensor.h"
+
+namespace phi {
+template <typename T, typename Context>
+void SequencePoolKernel(const Context& dev_ctx,
+                        const DenseTensor& x,
+                        bool is_test,
+                        const std::string& pooltype,
+                        float pad_value,
+                        DenseTensor* out,
+                        DenseTensor* max_index);
+
+}  // namespace phi