Fix Khatri-Rao test build (#9081)
Fix Khatri-Rao test build (#9081)

A recent inclusion of the Khatri-Rao operator breaks `make test`. We add a
missing include to resolve the error.

Fixes Issue #9076
jennyzhang0215/incubator-mxnet,fullfanta/mxnet,yajiedesign/mxnet,jiajiechen/mxnet,mbaijal/incubator-mxnet,jiajiechen/mxnet,jamesliu/mxnet,LinkHS/incubator-mxnet,fullfanta/mxnet,luoyetx/mxnet,dmlc/mxnet,CodingCat/mxnet,larroy/mxnet,ptrendx/mxnet,rahul003/mxnet,reminisce/mxnet,vikingMei/mxnet,luoyetx/mxnet,szha/mxnet,tornadomeet/mxnet,ykim362/mxnet,larroy/mxnet,larroy/mxnet,precedenceguo/mxnet,precedenceguo/mxnet,sxjscience/mxnet,ykim362/mxnet,vikingMei/mxnet,ptrendx/mxnet,luoyetx/mxnet,ptrendx/mxnet,precedenceguo/mxnet,reminisce/mxnet,ForkedReposBak/mxnet,szha/mxnet,dmlc/mxnet,jamesliu/mxnet,dmlc/mxnet,fullfanta/mxnet,CodingCat/mxnet,yuruofeifei/mxnet,jennyzhang0215/incubator-mxnet,Northrend/mxnet,Northrend/mxnet,yajiedesign/mxnet,weleen/mxnet,vikingMei/mxnet,dmlc/mxnet,apache/incubator-mxnet,ptrendx/mxnet,TuSimple/mxnet,reminisce/mxnet,jennyzhang0215/incubator-mxnet,ForkedReposBak/mxnet,mbaijal/incubator-mxnet,eric-haibin-lin/mxnet,luoyetx/mxnet,jamesliu/mxnet,leezu/mxnet,szha/mxnet,mbaijal/incubator-mxnet,TuSimple/mxnet,navrasio/mxnet,ForkedReposBak/mxnet,zhreshold/mxnet,szha/mxnet,eric-haibin-lin/mxnet,apache/incubator-mxnet,tornadomeet/mxnet,ykim362/mxnet,ptrendx/mxnet,navrasio/mxnet,navrasio/mxnet,DickJC123/mxnet,reminisce/mxnet,larroy/mxnet,leezu/mxnet,LinkHS/incubator-mxnet,TuSimple/mxnet,yajiedesign/mxnet,luoyetx/mxnet,LinkHS/incubator-mxnet,weleen/mxnet,weleen/mxnet,indhub/mxnet,dmlc/mxnet,larroy/mxnet,mbaijal/incubator-mxnet,LinkHS/incubator-mxnet,larroy/mxnet,navrasio/mxnet,indhub/mxnet,tlby/mxnet,tlby/mxnet,precedenceguo/mxnet,apache/incubator-mxnet,ykim362/mxnet,rahul003/mxnet,LinkHS/incubator-mxnet,CodingCat/mxnet,yajiedesign/mxnet,zhreshold/mxnet,ForkedReposBak/mxnet,larroy/mxnet,mbaijal/incubator-mxnet,tornadomeet/mxnet,reminisce/mxnet,leezu/mxnet,leezu/mxnet,jiajiechen/mxnet,fullfanta/mxnet,dmlc/mxnet,weleen/mxnet,tlby/mxnet,ykim362/mxnet,LinkHS/incubator-mxnet,precedenceguo/mxnet,eric-haibin-lin/mxnet,reminisce/mxnet,tornadomeet/mxnet,yuruofeifei/mxnet,CodingCat/mxnet,reminisce/mxnet,jamesliu/mxnet,szha/mxnet,Northrend/mxnet,yajiedesign/mxnet,jiajiechen/mxnet,tlby/mxnet,leezu/mxnet,tlby/mxnet,luoyetx/mxnet,weleen/mxnet,navrasio/mxnet,ForkedReposBak/mxnet,tlby/mxnet,zhreshold/mxnet,ptrendx/mxnet,navrasio/mxnet,jennyzhang0215/incubator-mxnet,TuSimple/mxnet,tornadomeet/mxnet,zhreshold/mxnet,yajiedesign/mxnet,eric-haibin-lin/mxnet,ptrendx/mxnet,rahul003/mxnet,yajiedesign/mxnet,tlby/mxnet,szha/mxnet,zhreshold/mxnet,ptrendx/mxnet,TuSimple/mxnet,ForkedReposBak/mxnet,ForkedReposBak/mxnet,ForkedReposBak/mxnet,eric-haibin-lin/mxnet,Northrend/mxnet,leezu/mxnet,LinkHS/incubator-mxnet,eric-haibin-lin/mxnet,precedenceguo/mxnet,fullfanta/mxnet,navrasio/mxnet,tornadomeet/mxnet,vikingMei/mxnet,yuruofeifei/mxnet,eric-haibin-lin/mxnet,TuSimple/mxnet,jiajiechen/mxnet,sxjscience/mxnet,yuruofeifei/mxnet,vikingMei/mxnet,leezu/mxnet,zhreshold/mxnet,szha/mxnet,indhub/mxnet,tornadomeet/mxnet,rahul003/mxnet,fullfanta/mxnet,vikingMei/mxnet,rahul003/mxnet,LinkHS/incubator-mxnet,vikingMei/mxnet,jamesliu/mxnet,sxjscience/mxnet,indhub/mxnet,reminisce/mxnet,fullfanta/mxnet,indhub/mxnet,yuruofeifei/mxnet,DickJC123/mxnet,navrasio/mxnet,tlby/mxnet,larroy/mxnet,weleen/mxnet,jamesliu/mxnet,rahul003/mxnet,DickJC123/mxnet,yajiedesign/mxnet,vikingMei/mxnet,navrasio/mxnet,weleen/mxnet,jamesliu/mxnet,yajiedesign/mxnet,zhreshold/mxnet,CodingCat/mxnet,fullfanta/mxnet,zhreshold/mxnet,jiajiechen/mxnet,vikingMei/mxnet,weleen/mxnet,luoyetx/mxnet,dmlc/mxnet,yuruofeifei/mxnet,rahul003/mxnet,mbaijal/incubator-mxnet,indhub/mxnet,szha/mxnet,DickJC123/mxnet,luoyetx/mxnet,CodingCat/mxnet,Northrend/mxnet,jamesliu/mxnet,rahul003/mxnet,leezu/mxnet,ykim362/mxnet,TuSimple/mxnet,precedenceguo/mxnet,indhub/mxnet,dmlc/mxnet,jiajiechen/mxnet,sxjscience/mxnet,precedenceguo/mxnet,jennyzhang0215/incubator-mxnet,sxjscience/mxnet,LinkHS/incubator-mxnet,jennyzhang0215/incubator-mxnet,ykim362/mxnet,ptrendx/mxnet,CodingCat/mxnet,leezu/mxnet,jiajiechen/mxnet,yuruofeifei/mxnet,indhub/mxnet,jennyzhang0215/incubator-mxnet,reminisce/mxnet,sxjscience/mxnet,precedenceguo/mxnet,eric-haibin-lin/mxnet,reminisce/mxnet,yuruofeifei/mxnet,TuSimple/mxnet,CodingCat/mxnet,apache/incubator-mxnet,sxjscience/mxnet,Northrend/mxnet,tlby/mxnet,szha/mxnet,larroy/mxnet,Northrend/mxnet,rahul003/mxnet,weleen/mxnet,sxjscience/mxnet,ykim362/mxnet,fullfanta/mxnet,luoyetx/mxnet,mbaijal/incubator-mxnet,dmlc/mxnet,yuruofeifei/mxnet,TuSimple/mxnet,indhub/mxnet,ptrendx/mxnet,CodingCat/mxnet,tornadomeet/mxnet,TuSimple/mxnet,tlby/mxnet,Northrend/mxnet,jiajiechen/mxnet,mbaijal/incubator-mxnet,mbaijal/incubator-mxnet,jennyzhang0215/incubator-mxnet,eric-haibin-lin/mxnet,ForkedReposBak/mxnet,Northrend/mxnet,zhreshold/mxnet,jennyzhang0215/incubator-mxnet,jamesliu/mxnet,ykim362/mxnet,tornadomeet/mxnet,sxjscience/mxnet