Replace temporary implementation in F.softmax_cross_entropy's ChainerX path
Replace temporary implementation in F.softmax_cross_entropy's ChainerX path

chainer/chainer,hvy/chainer,chainer/chainer,hvy/chainer,niboshi/chainer,chainer/chainer,niboshi/chainer,niboshi/chainer,hvy/chainer,hvy/chainer,niboshi/chainer,pfnet/chainer,chainer/chainer