Fix for clang-tidy
Fix for clang-tidy

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