Fix build for Cython 0.23
Fix build for Cython 0.23

hvy/chainer,keisuke-umezawa/chainer,tkerola/chainer,wkentaro/chainer,okuta/chainer,chainer/chainer,anaruse/chainer,keisuke-umezawa/chainer,aonotas/chainer,niboshi/chainer,rezoo/chainer,niboshi/chainer,jnishi/chainer,chainer/chainer,cupy/cupy,keisuke-umezawa/chainer,jnishi/chainer,cupy/cupy,pfnet/chainer,hvy/chainer,kiyukuta/chainer,cupy/cupy,jnishi/chainer,ktnyt/chainer,ronekko/chainer,kashif/chainer,ktnyt/chainer,jnishi/chainer,chainer/chainer,wkentaro/chainer,ktnyt/chainer,chainer/chainer,keisuke-umezawa/chainer,cupy/cupy,niboshi/chainer,delta2323/chainer,hvy/chainer,okuta/chainer,ysekky/chainer,ktnyt/chainer,wkentaro/chainer,niboshi/chainer,hvy/chainer,wkentaro/chainer,okuta/chainer,okuta/chainer