add default value for return_type in MxFuncGetInfo so it is compatible with old code
add default value for return_type in MxFuncGetInfo so it is compatible with old code

arank/mxnet,jermainewang/mxnet,Prasad9/incubator-mxnet,jermainewang/mxnet,Ldpe2G/mxnet,dmlc/mxnet,rishita/mxnet,luoyetx/mxnet,jermainewang/mxnet,lxn2/mxnet,vikingMei/mxnet,madjam/mxnet,thirdwing/mxnet,hesseltuinhof/mxnet,navrasio/mxnet,wangyum/mxnet,thirdwing/mxnet,leezu/mxnet,rishita/mxnet,formath/mxnet,Northrend/mxnet,luoyetx/mxnet,navrasio/mxnet,eric-haibin-lin/mxnet,sxjscience/mxnet,saurabh3949/mxnet,kkk669/mxnet,indhub/mxnet,thirdwing/mxnet,wangyum/mxnet,weleen/mxnet,coder-james/mxnet,dmlc/mxnet,gautamkmr/incubator-mxnet,jiajiechen/mxnet,precedenceguo/mxnet,Guneet-Dhillon/mxnet,zhreshold/mxnet,hpi-xnor/BMXNet,antoan2/incubator-mxnet,smolix/incubator-mxnet,ShownX/incubator-mxnet,gautamkmr/incubator-mxnet,yajiedesign/mxnet,sergeykolychev/mxnet,dmlc/mxnet,piiswrong/mxnet,precedenceguo/mxnet,Ldpe2G/mxnet,smolix/incubator-mxnet,nicklhy/mxnet,sergeykolychev/mxnet,Guneet-Dhillon/mxnet,ptrendx/mxnet,LinkHS/incubator-mxnet,yajiedesign/mxnet,jamesliu/mxnet,danithaca/mxnet,larroy/mxnet,jennyzhang0215/incubator-mxnet,sergeykolychev/mxnet,ShownX/incubator-mxnet,danithaca/mxnet,mbaijal/incubator-mxnet,gautamkmr/incubator-mxnet,fullfanta/mxnet,tlby/mxnet,lxn2/mxnet,jennyzhang0215/incubator-mxnet,tlby/mxnet,Northrend/mxnet,sxjscience/mxnet,hesseltuinhof/mxnet,sergeykolychev/mxnet,yajiedesign/mxnet,pluskid/mxnet,danithaca/mxnet,indhub/mxnet,arikpoz/mxnet,Guneet-Dhillon/mxnet,leezu/mxnet,nicklhy/mxnet,nicklhy/mxnet,formath/mxnet,likelyzhao/mxnet,mbaijal/incubator-mxnet,apaleyes/mxnet,szha/mxnet,solin319/incubator-mxnet,hotpxl/mxnet,madjam/mxnet,Ldpe2G/mxnet,mbaijal/incubator-mxnet,LinkHS/incubator-mxnet,larroy/mxnet,hesseltuinhof/mxnet,jiajiechen/mxnet,madjam/mxnet,yuruofeifei/mxnet,ForkedReposBak/mxnet,ptrendx/mxnet,LinkHS/incubator-mxnet,Guneet-Dhillon/mxnet,larroy/mxnet,yajiedesign/mxnet,ShownX/incubator-mxnet,eric-haibin-lin/mxnet,antoan2/incubator-mxnet,weleen/mxnet,szha/mxnet,piiswrong/mxnet,ptrendx/mxnet,hpi-xnor/BMXNet,tornadomeet/mxnet,hpi-xnor/BMXNet,gautamkmr/incubator-mxnet,Ldpe2G/mxnet,leezu/mxnet,ZihengJiang/mxnet,madjam/mxnet,vikingMei/mxnet,sxjscience/mxnet,jamesliu/mxnet,arank/mxnet,coder-james/mxnet,ShownX/incubator-mxnet,LinkHS/incubator-mxnet,TuSimple/mxnet,jamesliu/mxnet,solin319/incubator-mxnet,kevinthesun/mxnet,reminisce/mxnet,crazy-cat/incubator-mxnet,lxn2/mxnet,likelyzhao/mxnet,hesseltuinhof/mxnet,antoan2/incubator-mxnet,mbaijal/incubator-mxnet,jamesliu/mxnet,EvanzzzZ/mxnet,ykim362/mxnet,rahul003/mxnet,hesseltuinhof/mxnet,Guneet-Dhillon/mxnet,piiswrong/mxnet,larroy/mxnet,lxn2/mxnet,stefanhenneking/mxnet,nicklhy/mxnet,zhreshold/mxnet,reminisce/mxnet,formath/mxnet,Northrend/mxnet,indhub/mxnet,wangyum/mxnet,coder-james/mxnet,Guneet-Dhillon/mxnet,piiswrong/mxnet,luoyetx/mxnet,jennyzhang0215/incubator-mxnet,jennyzhang0215/incubator-mxnet,stefanhenneking/mxnet,LinkHS/incubator-mxnet,smolix/incubator-mxnet,gautamkmr/incubator-mxnet,ptrendx/mxnet,ykim362/mxnet,eric-haibin-lin/mxnet,Northrend/mxnet,apaleyes/mxnet,gautamkmr/incubator-mxnet,formath/mxnet,nicklhy/mxnet,reminisce/mxnet,tlby/mxnet,kevinthesun/mxnet,szha/mxnet,Mega-DatA-Lab/mxnet,vikingMei/mxnet,madjam/mxnet,reminisce/mxnet,Mega-DatA-Lab/mxnet,navrasio/mxnet,yajiedesign/mxnet,madjam/mxnet,vikingMei/mxnet,danithaca/mxnet,apache/incubator-mxnet,LinkHS/incubator-mxnet,rishita/mxnet,tlby/mxnet,Northrend/mxnet,arank/mxnet,crazy-cat/incubator-mxnet,thirdwing/mxnet,pluskid/mxnet,ykim362/mxnet,jermainewang/mxnet,Northrend/mxnet,nicklhy/mxnet,jiajiechen/mxnet,Prasad9/incubator-mxnet,dmlc/mxnet,thirdwing/mxnet,vikingMei/mxnet,DR08/mxnet,stefanhenneking/mxnet,arikpoz/mxnet,wangyum/mxnet,stefanhenneking/mxnet,saurabh3949/mxnet,ykim362/mxnet,EvanzzzZ/mxnet,likelyzhao/mxnet,Prasad9/incubator-mxnet,coder-james/mxnet,crazy-cat/incubator-mxnet,jamesliu/mxnet,formath/mxnet,fullfanta/mxnet,TuSimple/mxnet,szha/mxnet,larroy/mxnet,ykim362/mxnet,navrasio/mxnet,sergeykolychev/mxnet,ZihengJiang/mxnet,xcgoner/dist-mxnet,kkk669/mxnet,solin319/incubator-mxnet,szha/mxnet,rishita/mxnet,madjam/mxnet,vikingMei/mxnet,leezu/mxnet,tlby/mxnet,mbaijal/incubator-mxnet,madjam/mxnet,luoyetx/mxnet,ykim362/mxnet,ForkedReposBak/mxnet,pluskid/mxnet,hotpxl/mxnet,apaleyes/mxnet,gautamkmr/incubator-mxnet,EvanzzzZ/mxnet,nicklhy/mxnet,rishita/mxnet,hotpxl/mxnet,ForkedReposBak/mxnet,solin319/incubator-mxnet,tornadomeet/mxnet,jermainewang/mxnet,wangyum/mxnet,crazy-cat/incubator-mxnet,hpi-xnor/BMXNet,stefanhenneking/mxnet,piiswrong/mxnet,Prasad9/incubator-mxnet,CodingCat/mxnet,jiajiechen/mxnet,larroy/mxnet,coder-james/mxnet,mbaijal/incubator-mxnet,Guneet-Dhillon/mxnet,LinkHS/incubator-mxnet,EvanzzzZ/mxnet,TuSimple/mxnet,rahul003/mxnet,LinkHS/incubator-mxnet,sxjscience/mxnet,coder-james/mxnet,formath/mxnet,ForkedReposBak/mxnet,CodingCat/mxnet,saurabh3949/mxnet,indhub/mxnet,sxjscience/mxnet,crazy-cat/incubator-mxnet,precedenceguo/mxnet,ZihengJiang/mxnet,kkk669/mxnet,zhreshold/mxnet,Mega-DatA-Lab/mxnet,fullfanta/mxnet,navrasio/mxnet,Mega-DatA-Lab/mxnet,arikpoz/mxnet,ForkedReposBak/mxnet,jiajiechen/mxnet,jamesliu/mxnet,arikpoz/mxnet,sxjscience/mxnet,reminisce/mxnet,DR08/mxnet,rahul003/mxnet,lxn2/mxnet,luoyetx/mxnet,madjam/mxnet,tlby/mxnet,xcgoner/dist-mxnet,smolix/incubator-mxnet,apaleyes/mxnet,arank/mxnet,apaleyes/mxnet,crazy-cat/incubator-mxnet,smolix/incubator-mxnet,Ldpe2G/mxnet,gautamkmr/incubator-mxnet,hesseltuinhof/mxnet,weleen/mxnet,reminisce/mxnet,yuruofeifei/mxnet,leezu/mxnet,zhreshold/mxnet,stefanhenneking/mxnet,luoyetx/mxnet,saurabh3949/mxnet,Mega-DatA-Lab/mxnet,DickJC123/mxnet,indhub/mxnet,ZihengJiang/mxnet,TuSimple/mxnet,rishita/mxnet,arank/mxnet,thirdwing/mxnet,xcgoner/dist-mxnet,jamesliu/mxnet,vikingMei/mxnet,jennyzhang0215/incubator-mxnet,xcgoner/dist-mxnet,lxn2/mxnet,hotpxl/mxnet,apaleyes/mxnet,coder-james/mxnet,xcgoner/dist-mxnet,tornadomeet/mxnet,DR08/mxnet,hpi-xnor/BMXNet,sxjscience/mxnet,danithaca/mxnet,dmlc/mxnet,nicklhy/mxnet,stefanhenneking/mxnet,yuruofeifei/mxnet,sergeykolychev/mxnet,jennyzhang0215/incubator-mxnet,lxn2/mxnet,kkk669/mxnet,indhub/mxnet,precedenceguo/mxnet,DickJC123/mxnet,tornadomeet/mxnet,navrasio/mxnet,yuruofeifei/mxnet,jermainewang/mxnet,eric-haibin-lin/mxnet,hesseltuinhof/mxnet,TuSimple/mxnet,ptrendx/mxnet,xcgoner/dist-mxnet,crazy-cat/incubator-mxnet,apache/incubator-mxnet,kkk669/mxnet,weleen/mxnet,pluskid/mxnet,rishita/mxnet,weleen/mxnet,weleen/mxnet,rahul003/mxnet,jamesliu/mxnet,solin319/incubator-mxnet,arank/mxnet,Prasad9/incubator-mxnet,yajiedesign/mxnet,tlby/mxnet,lxn2/mxnet,antoan2/incubator-mxnet,weleen/mxnet,danithaca/mxnet,tornadomeet/mxnet,sxjscience/mxnet,xcgoner/dist-mxnet,LinkHS/incubator-mxnet,ForkedReposBak/mxnet,jermainewang/mxnet,tornadomeet/mxnet,hotpxl/mxnet,ykim362/mxnet,ykim362/mxnet,apaleyes/mxnet,hotpxl/mxnet,likelyzhao/mxnet,jermainewang/mxnet,larroy/mxnet,Mega-DatA-Lab/mxnet,kevinthesun/mxnet,EvanzzzZ/mxnet,indhub/mxnet,dmlc/mxnet,DickJC123/mxnet,Prasad9/incubator-mxnet,jiajiechen/mxnet,TuSimple/mxnet,pluskid/mxnet,tlby/mxnet,yuruofeifei/mxnet,navrasio/mxnet,tornadomeet/mxnet,antoan2/incubator-mxnet,jennyzhang0215/incubator-mxnet,zhreshold/mxnet,DR08/mxnet,fullfanta/mxnet,pluskid/mxnet,luoyetx/mxnet,precedenceguo/mxnet,jiajiechen/mxnet,leezu/mxnet,hesseltuinhof/mxnet,coder-james/mxnet,xcgoner/dist-mxnet,arank/mxnet,ForkedReposBak/mxnet,DR08/mxnet,precedenceguo/mxnet,Ldpe2G/mxnet,Northrend/mxnet,saurabh3949/mxnet,thirdwing/mxnet,smolix/incubator-mxnet,hpi-xnor/BMXNet,yajiedesign/mxnet,Northrend/mxnet,wangyum/mxnet,likelyzhao/mxnet,kkk669/mxnet,szha/mxnet,leezu/mxnet,yuruofeifei/mxnet,Ldpe2G/mxnet,hotpxl/mxnet,rishita/mxnet,kevinthesun/mxnet,saurabh3949/mxnet,sergeykolychev/mxnet,ShownX/incubator-mxnet,saurabh3949/mxnet,arikpoz/mxnet,Mega-DatA-Lab/mxnet,apaleyes/mxnet,thirdwing/mxnet,reminisce/mxnet,hotpxl/mxnet,eric-haibin-lin/mxnet,arank/mxnet,arank/mxnet,coder-james/mxnet,vikingMei/mxnet,formath/mxnet,eric-haibin-lin/mxnet,kevinthesun/mxnet,rishita/mxnet,arikpoz/mxnet,szha/mxnet,indhub/mxnet,yuruofeifei/mxnet,Guneet-Dhillon/mxnet,eric-haibin-lin/mxnet,ZihengJiang/mxnet,szha/mxnet,solin319/incubator-mxnet,saurabh3949/mxnet,rahul003/mxnet,reminisce/mxnet,CodingCat/mxnet,likelyzhao/mxnet,kkk669/mxnet,sxjscience/mxnet,zhreshold/mxnet,CodingCat/mxnet,jennyzhang0215/incubator-mxnet,EvanzzzZ/mxnet,tornadomeet/mxnet,arikpoz/mxnet,antoan2/incubator-mxnet,stefanhenneking/mxnet,wangyum/mxnet,kevinthesun/mxnet,kevinthesun/mxnet,pluskid/mxnet,stefanhenneking/mxnet,arikpoz/mxnet,hesseltuinhof/mxnet,sergeykolychev/mxnet,yuruofeifei/mxnet,CodingCat/mxnet,mbaijal/incubator-mxnet,gautamkmr/incubator-mxnet,precedenceguo/mxnet,Prasad9/incubator-mxnet,dmlc/mxnet,leezu/mxnet,DR08/mxnet,piiswrong/mxnet,piiswrong/mxnet,crazy-cat/incubator-mxnet,Ldpe2G/mxnet,ZihengJiang/mxnet,reminisce/mxnet,ptrendx/mxnet,jennyzhang0215/incubator-mxnet,luoyetx/mxnet,danithaca/mxnet,ykim362/mxnet,mbaijal/incubator-mxnet,rahul003/mxnet,CodingCat/mxnet,tlby/mxnet,leezu/mxnet,zhreshold/mxnet,pluskid/mxnet,fullfanta/mxnet,tornadomeet/mxnet,nicklhy/mxnet,antoan2/incubator-mxnet,kkk669/mxnet,yajiedesign/mxnet,xcgoner/dist-mxnet,yajiedesign/mxnet,Northrend/mxnet,jamesliu/mxnet,eric-haibin-lin/mxnet,zhreshold/mxnet,EvanzzzZ/mxnet,weleen/mxnet,ZihengJiang/mxnet,danithaca/mxnet,DR08/mxnet,danithaca/mxnet,ShownX/incubator-mxnet,formath/mxnet,hpi-xnor/BMXNet,hpi-xnor/BMXNet,luoyetx/mxnet,fullfanta/mxnet,DickJC123/mxnet,apache/incubator-mxnet,kkk669/mxnet,lxn2/mxnet,ShownX/incubator-mxnet,Prasad9/incubator-mxnet,solin319/incubator-mxnet,crazy-cat/incubator-mxnet,DR08/mxnet,larroy/mxnet,arikpoz/mxnet,Mega-DatA-Lab/mxnet,larroy/mxnet,zhreshold/mxnet,yuruofeifei/mxnet,piiswrong/mxnet,solin319/incubator-mxnet,indhub/mxnet,TuSimple/mxnet,wangyum/mxnet,rahul003/mxnet,likelyzhao/mxnet,CodingCat/mxnet,ZihengJiang/mxnet,precedenceguo/mxnet,jiajiechen/mxnet,pluskid/mxnet,wangyum/mxnet,eric-haibin-lin/mxnet,CodingCat/mxnet,dmlc/mxnet,precedenceguo/mxnet,EvanzzzZ/mxnet,rahul003/mxnet,reminisce/mxnet,CodingCat/mxnet,TuSimple/mxnet,mbaijal/incubator-mxnet,jiajiechen/mxnet,navrasio/mxnet,ShownX/incubator-mxnet,solin319/incubator-mxnet,apaleyes/mxnet,EvanzzzZ/mxnet,Ldpe2G/mxnet,likelyzhao/mxnet,jermainewang/mxnet,fullfanta/mxnet,ptrendx/mxnet,kevinthesun/mxnet,ptrendx/mxnet,ForkedReposBak/mxnet,fullfanta/mxnet,antoan2/incubator-mxnet,dmlc/mxnet,TuSimple/mxnet,weleen/mxnet,likelyzhao/mxnet,rahul003/mxnet,Guneet-Dhillon/mxnet,ptrendx/mxnet,kevinthesun/mxnet,smolix/incubator-mxnet,hpi-xnor/BMXNet,smolix/incubator-mxnet,DR08/mxnet,szha/mxnet,tlby/mxnet,vikingMei/mxnet,ZihengJiang/mxnet,ForkedReposBak/mxnet,hotpxl/mxnet,ShownX/incubator-mxnet,piiswrong/mxnet,smolix/incubator-mxnet,fullfanta/mxnet,formath/mxnet,Mega-DatA-Lab/mxnet,TuSimple/mxnet,apache/incubator-mxnet,saurabh3949/mxnet,thirdwing/mxnet,navrasio/mxnet,antoan2/incubator-mxnet,Prasad9/incubator-mxnet,sergeykolychev/mxnet,ptrendx/mxnet