[Example]Refactor alexnet cpp example (#13278)
[Example]Refactor alexnet cpp example (#13278)

* delete print to make the log more clean

* delete the log user don't need

sxjscience/mxnet,szha/mxnet,ForkedReposBak/mxnet,dmlc/mxnet,ptrendx/mxnet,yajiedesign/mxnet,ForkedReposBak/mxnet,sxjscience/mxnet,zhreshold/mxnet,sxjscience/mxnet,eric-haibin-lin/mxnet,leezu/mxnet,tlby/mxnet,larroy/mxnet,DickJC123/mxnet,ForkedReposBak/mxnet,DickJC123/mxnet,ptrendx/mxnet,eric-haibin-lin/mxnet,zhreshold/mxnet,dmlc/mxnet,szha/mxnet,ptrendx/mxnet,dmlc/mxnet,reminisce/mxnet,apache/incubator-mxnet,dmlc/mxnet,sxjscience/mxnet,leezu/mxnet,ptrendx/mxnet,yajiedesign/mxnet,ForkedReposBak/mxnet,tlby/mxnet,szha/mxnet,eric-haibin-lin/mxnet,yajiedesign/mxnet,dmlc/mxnet,eric-haibin-lin/mxnet,zhreshold/mxnet,eric-haibin-lin/mxnet,sxjscience/mxnet,yajiedesign/mxnet,yajiedesign/mxnet,ForkedReposBak/mxnet,yajiedesign/mxnet,zhreshold/mxnet,tlby/mxnet,eric-haibin-lin/mxnet,reminisce/mxnet,tlby/mxnet,leezu/mxnet,tlby/mxnet,ptrendx/mxnet,szha/mxnet,szha/mxnet,leezu/mxnet,tlby/mxnet,ptrendx/mxnet,sxjscience/mxnet,yajiedesign/mxnet,leezu/mxnet,larroy/mxnet,dmlc/mxnet,ptrendx/mxnet,leezu/mxnet,apache/incubator-mxnet,DickJC123/mxnet,tlby/mxnet,zhreshold/mxnet,apache/incubator-mxnet,sxjscience/mxnet,sxjscience/mxnet,dmlc/mxnet,larroy/mxnet,zhreshold/mxnet,dmlc/mxnet,szha/mxnet,eric-haibin-lin/mxnet,reminisce/mxnet,yajiedesign/mxnet,tlby/mxnet,larroy/mxnet,szha/mxnet,reminisce/mxnet,ForkedReposBak/mxnet,ForkedReposBak/mxnet,zhreshold/mxnet,larroy/mxnet,tlby/mxnet,ForkedReposBak/mxnet,ptrendx/mxnet,leezu/mxnet,larroy/mxnet,eric-haibin-lin/mxnet,zhreshold/mxnet,reminisce/mxnet,reminisce/mxnet,ForkedReposBak/mxnet,dmlc/mxnet,szha/mxnet,DickJC123/mxnet,apache/incubator-mxnet,reminisce/mxnet,larroy/mxnet,eric-haibin-lin/mxnet,szha/mxnet,leezu/mxnet,sxjscience/mxnet,zhreshold/mxnet,ptrendx/mxnet,leezu/mxnet,yajiedesign/mxnet,reminisce/mxnet,reminisce/mxnet,larroy/mxnet,ptrendx/mxnet,reminisce/mxnet,larroy/mxnet,tlby/mxnet