Support ChainerX in cifar example
Support ChainerX in cifar example

wkentaro/chainer,keisuke-umezawa/chainer,keisuke-umezawa/chainer,okuta/chainer,hvy/chainer,okuta/chainer,niboshi/chainer,wkentaro/chainer,niboshi/chainer,tkerola/chainer,pfnet/chainer,niboshi/chainer,niboshi/chainer,wkentaro/chainer,chainer/chainer,keisuke-umezawa/chainer,hvy/chainer,chainer/chainer,okuta/chainer,chainer/chainer,hvy/chainer,chainer/chainer,okuta/chainer,keisuke-umezawa/chainer,wkentaro/chainer,hvy/chainer