Improve sparse.retain performance on CPU  (#9722)
Improve sparse.retain performance on CPU  (#9722)

* first commit

* add missing file

* remove switch

* remove script

* fix lint

precedenceguo/mxnet,TuSimple/mxnet,luoyetx/mxnet,zhreshold/mxnet,eric-haibin-lin/mxnet,luoyetx/mxnet,TuSimple/mxnet,szha/mxnet,reminisce/mxnet,ptrendx/mxnet,TuSimple/mxnet,ForkedReposBak/mxnet,TuSimple/mxnet,jamesliu/mxnet,reminisce/mxnet,tornadomeet/mxnet,jamesliu/mxnet,precedenceguo/mxnet,zhreshold/mxnet,apache/incubator-mxnet,TuSimple/mxnet,rahul003/mxnet,leezu/mxnet,precedenceguo/mxnet,tornadomeet/mxnet,LinkHS/incubator-mxnet,reminisce/mxnet,TuSimple/mxnet,mbaijal/incubator-mxnet,mbaijal/incubator-mxnet,tlby/mxnet,zhreshold/mxnet,luoyetx/mxnet,tlby/mxnet,dmlc/mxnet,fullfanta/mxnet,LinkHS/incubator-mxnet,eric-haibin-lin/mxnet,jiajiechen/mxnet,precedenceguo/mxnet,navrasio/mxnet,ForkedReposBak/mxnet,CodingCat/mxnet,jiajiechen/mxnet,tlby/mxnet,eric-haibin-lin/mxnet,ForkedReposBak/mxnet,luoyetx/mxnet,jamesliu/mxnet,fullfanta/mxnet,LinkHS/incubator-mxnet,LinkHS/incubator-mxnet,yajiedesign/mxnet,jiajiechen/mxnet,mbaijal/incubator-mxnet,zhreshold/mxnet,szha/mxnet,navrasio/mxnet,indhub/mxnet,fullfanta/mxnet,CodingCat/mxnet,reminisce/mxnet,reminisce/mxnet,jiajiechen/mxnet,szha/mxnet,jiajiechen/mxnet,jamesliu/mxnet,rahul003/mxnet,fullfanta/mxnet,fullfanta/mxnet,luoyetx/mxnet,CodingCat/mxnet,ptrendx/mxnet,mbaijal/incubator-mxnet,ptrendx/mxnet,CodingCat/mxnet,luoyetx/mxnet,tornadomeet/mxnet,indhub/mxnet,larroy/mxnet,indhub/mxnet,navrasio/mxnet,TuSimple/mxnet,LinkHS/incubator-mxnet,yajiedesign/mxnet,apache/incubator-mxnet,sxjscience/mxnet,fullfanta/mxnet,szha/mxnet,ptrendx/mxnet,rahul003/mxnet,fullfanta/mxnet,ptrendx/mxnet,dmlc/mxnet,sxjscience/mxnet,navrasio/mxnet,navrasio/mxnet,tornadomeet/mxnet,jiajiechen/mxnet,CodingCat/mxnet,navrasio/mxnet,dmlc/mxnet,rahul003/mxnet,larroy/mxnet,leezu/mxnet,yajiedesign/mxnet,zhreshold/mxnet,jiajiechen/mxnet,ForkedReposBak/mxnet,indhub/mxnet,ptrendx/mxnet,DickJC123/mxnet,tlby/mxnet,indhub/mxnet,larroy/mxnet,luoyetx/mxnet,sxjscience/mxnet,DickJC123/mxnet,zhreshold/mxnet,ForkedReposBak/mxnet,mbaijal/incubator-mxnet,larroy/mxnet,eric-haibin-lin/mxnet,precedenceguo/mxnet,sxjscience/mxnet,eric-haibin-lin/mxnet,reminisce/mxnet,CodingCat/mxnet,indhub/mxnet,apache/incubator-mxnet,szha/mxnet,szha/mxnet,mbaijal/incubator-mxnet,tlby/mxnet,ForkedReposBak/mxnet,CodingCat/mxnet,sxjscience/mxnet,zhreshold/mxnet,precedenceguo/mxnet,ptrendx/mxnet,yajiedesign/mxnet,TuSimple/mxnet,tornadomeet/mxnet,larroy/mxnet,dmlc/mxnet,tornadomeet/mxnet,precedenceguo/mxnet,tlby/mxnet,tlby/mxnet,TuSimple/mxnet,tlby/mxnet,sxjscience/mxnet,tornadomeet/mxnet,jiajiechen/mxnet,jiajiechen/mxnet,reminisce/mxnet,sxjscience/mxnet,mbaijal/incubator-mxnet,tornadomeet/mxnet,leezu/mxnet,leezu/mxnet,yajiedesign/mxnet,rahul003/mxnet,ForkedReposBak/mxnet,eric-haibin-lin/mxnet,leezu/mxnet,leezu/mxnet,yajiedesign/mxnet,LinkHS/incubator-mxnet,leezu/mxnet,eric-haibin-lin/mxnet,jamesliu/mxnet,navrasio/mxnet,luoyetx/mxnet,indhub/mxnet,LinkHS/incubator-mxnet,navrasio/mxnet,leezu/mxnet,zhreshold/mxnet,szha/mxnet,jamesliu/mxnet,larroy/mxnet,leezu/mxnet,rahul003/mxnet,jamesliu/mxnet,dmlc/mxnet,ptrendx/mxnet,yajiedesign/mxnet,indhub/mxnet,navrasio/mxnet,fullfanta/mxnet,tlby/mxnet,jamesliu/mxnet,TuSimple/mxnet,yajiedesign/mxnet,sxjscience/mxnet,luoyetx/mxnet,larroy/mxnet,tornadomeet/mxnet,dmlc/mxnet,fullfanta/mxnet,yajiedesign/mxnet,precedenceguo/mxnet,apache/incubator-mxnet,larroy/mxnet,rahul003/mxnet,dmlc/mxnet,reminisce/mxnet,DickJC123/mxnet,zhreshold/mxnet,LinkHS/incubator-mxnet,sxjscience/mxnet,mbaijal/incubator-mxnet,CodingCat/mxnet,indhub/mxnet,eric-haibin-lin/mxnet,dmlc/mxnet,LinkHS/incubator-mxnet,jamesliu/mxnet,mbaijal/incubator-mxnet,ptrendx/mxnet,dmlc/mxnet,ForkedReposBak/mxnet,eric-haibin-lin/mxnet,reminisce/mxnet,ptrendx/mxnet,szha/mxnet,rahul003/mxnet,rahul003/mxnet,tlby/mxnet,reminisce/mxnet,CodingCat/mxnet,DickJC123/mxnet,szha/mxnet,larroy/mxnet,precedenceguo/mxnet,ForkedReposBak/mxnet