Rewrite sequence pooling last and first mode with memcpy and clean code
Rewrite sequence pooling last and first mode with memcpy and clean code

reyoung/Paddle,baidu/Paddle,luotao1/Paddle,chengduoZH/Paddle,chengduoZH/Paddle,baidu/Paddle,reyoung/Paddle,PaddlePaddle/Paddle,chengduoZH/Paddle,luotao1/Paddle,baidu/Paddle,reyoung/Paddle,PaddlePaddle/Paddle,baidu/Paddle,luotao1/Paddle,tensor-tang/Paddle,tensor-tang/Paddle,PaddlePaddle/Paddle,chengduoZH/Paddle,reyoung/Paddle,PaddlePaddle/Paddle,PaddlePaddle/Paddle,chengduoZH/Paddle,luotao1/Paddle,tensor-tang/Paddle,reyoung/Paddle,tensor-tang/Paddle,reyoung/Paddle,luotao1/Paddle,tensor-tang/Paddle,PaddlePaddle/Paddle,luotao1/Paddle,PaddlePaddle/Paddle,luotao1/Paddle,baidu/Paddle