Fix eval for N_test smaller than batch_size
Fix eval for N_test smaller than batch_size

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