support nccl2 dist train in trainer
support nccl2 dist train in trainer

baidu/Paddle,PaddlePaddle/Paddle,chengduoZH/Paddle,QiJune/Paddle,Canpio/Paddle,PaddlePaddle/Paddle,Canpio/Paddle,chengduoZH/Paddle,Canpio/Paddle,pkuyym/Paddle,jacquesqiao/Paddle,pkuyym/Paddle,baidu/Paddle,PaddlePaddle/Paddle,QiJune/Paddle,reyoung/Paddle,reyoung/Paddle,putcn/Paddle,PaddlePaddle/Paddle,tensor-tang/Paddle,tensor-tang/Paddle,luotao1/Paddle,QiJune/Paddle,reyoung/Paddle,PaddlePaddle/Paddle,luotao1/Paddle,tensor-tang/Paddle,Canpio/Paddle,baidu/Paddle,jacquesqiao/Paddle,pkuyym/Paddle,luotao1/Paddle,PaddlePaddle/Paddle,luotao1/Paddle,reyoung/Paddle,putcn/Paddle,QiJune/Paddle,luotao1/Paddle,putcn/Paddle,reyoung/Paddle,reyoung/Paddle,baidu/Paddle,PaddlePaddle/Paddle,chengduoZH/Paddle,baidu/Paddle,pkuyym/Paddle,chengduoZH/Paddle,QiJune/Paddle,Canpio/Paddle,Canpio/Paddle,tensor-tang/Paddle,putcn/Paddle,tensor-tang/Paddle,Canpio/Paddle,pkuyym/Paddle,chengduoZH/Paddle,jacquesqiao/Paddle,jacquesqiao/Paddle,luotao1/Paddle,putcn/Paddle,jacquesqiao/Paddle,luotao1/Paddle,Canpio/Paddle,pkuyym/Paddle,QiJune/Paddle,jacquesqiao/Paddle,putcn/Paddle