Fix quick_start/preprocess.sh for dash
Fix quick_start/preprocess.sh for dash

On Ubuntu, /bin/sh is dash. Change to POSIX syntax

ISSUE=4607487

git-svn-id: 7b05817fec9a0a7f398a8fb38bca5f76eb450168@1455 1ad973e4-5ce8-4261-8a94-b56d1f490c56

hedaoyuan/Paddle,dayhaha/Paddle,tensor-tang/Paddle,chengduoZH/Paddle,hedaoyuan/Paddle,reyoung/Paddle,helinwang/Paddle,QiJune/Paddle,zhouxiao-coder/Paddle,pkuyym/Paddle,lispc/Paddle,zuowang/Paddle,tensor-tang/Paddle,qingqing01/Paddle,Canpio/Paddle,gangliao/Paddle,lispc/Paddle,livc/Paddle,reyoung/Paddle,putcn/Paddle,luotao1/Paddle,luotao1/Paddle,alvations/Paddle,tensor-tang/Paddle,pkuyym/Paddle,Canpio/Paddle,dayhaha/Paddle,emailweixu/Paddle,yu239/Paddle,lcy-seso/Paddle,lispc/Paddle,reyoung/Paddle,alvations/Paddle,emailweixu/Paddle,helinwang/Paddle,QiJune/Paddle,tensor-tang/Paddle,pkuyym/Paddle,reyoung/Paddle,yu239/Paddle,lcy-seso/Paddle,luotao1/Paddle,lcy-seso/Paddle,Canpio/Paddle,lcy-seso/Paddle,PaddlePaddle/Paddle,beckett1124/Paddle,gangliao/Paddle,chengduoZH/Paddle,yu239/Paddle,PaddlePaddle/Paddle,alvations/Paddle,yu239/Paddle,hedaoyuan/Paddle,zuowang/Paddle,zhouxiao-coder/Paddle,zhouxiao-coder/Paddle,putcn/Paddle,baidu/Paddle,cxysteven/Paddle,baidu/Paddle,lispc/Paddle,dayhaha/Paddle,pkuyym/Paddle,zuowang/Paddle,gangliao/Paddle,cxysteven/Paddle,pengli09/Paddle,pkuyym/Paddle,putcn/Paddle,zhouxiao-coder/Paddle,wen-bo-yang/Paddle,emailweixu/Paddle,Canpio/Paddle,wen-bo-yang/Paddle,beckett1124/Paddle,pengli09/Paddle,putcn/Paddle,QiJune/Paddle,wen-bo-yang/Paddle,PaddlePaddle/Paddle,wen-bo-yang/Paddle,lcy-seso/Paddle,cxysteven/Paddle,wen-bo-yang/Paddle,gangliao/Paddle,helinwang/Paddle,jacquesqiao/Paddle,reyoung/Paddle,comeonfox/Paddle,beckett1124/Paddle,tensor-tang/Paddle,chengduoZH/Paddle,wen-bo-yang/Paddle,dayhaha/Paddle,yu239/Paddle,livc/Paddle,zhouxiao-coder/Paddle,beckett1124/Paddle,luotao1/Paddle,jacquesqiao/Paddle,Canpio/Paddle,zhouxiao-coder/Paddle,cxysteven/Paddle,pengli09/Paddle,Canpio/Paddle,lcy-seso/Paddle,luotao1/Paddle,chengduoZH/Paddle,alvations/Paddle,dayhaha/Paddle,emailweixu/Paddle,lispc/Paddle,pengli09/Paddle,Canpio/Paddle,luotao1/Paddle,qingqing01/Paddle,wen-bo-yang/Paddle,lispc/Paddle,pengli09/Paddle,QiJune/Paddle,livc/Paddle,hedaoyuan/Paddle,beckett1124/Paddle,helinwang/Paddle,putcn/Paddle,jacquesqiao/Paddle,putcn/Paddle,cxysteven/Paddle,dayhaha/Paddle,lispc/Paddle,luotao1/Paddle,comeonfox/Paddle,Canpio/Paddle,zhouxiao-coder/Paddle,baidu/Paddle,livc/Paddle,comeonfox/Paddle,qingqing01/Paddle,cxysteven/Paddle,PaddlePaddle/Paddle,jacquesqiao/Paddle,hedaoyuan/Paddle,yu239/Paddle,comeonfox/Paddle,qingqing01/Paddle,PaddlePaddle/Paddle,livc/Paddle,gangliao/Paddle,zuowang/Paddle,QiJune/Paddle,yu239/Paddle,emailweixu/Paddle,lispc/Paddle,pengli09/Paddle,livc/Paddle,beckett1124/Paddle,zuowang/Paddle,helinwang/Paddle,helinwang/Paddle,baidu/Paddle,PaddlePaddle/Paddle,baidu/Paddle,QiJune/Paddle,jacquesqiao/Paddle,alvations/Paddle,beckett1124/Paddle,pengli09/Paddle,emailweixu/Paddle,jacquesqiao/Paddle,chengduoZH/Paddle,hedaoyuan/Paddle,cxysteven/Paddle,helinwang/Paddle,PaddlePaddle/Paddle,comeonfox/Paddle,pkuyym/Paddle,hedaoyuan/Paddle,dayhaha/Paddle,pengli09/Paddle,qingqing01/Paddle,reyoung/Paddle,livc/Paddle,yu239/Paddle,hedaoyuan/Paddle,emailweixu/Paddle,gangliao/Paddle,gangliao/Paddle