Revert "Add static qualifier"
Revert "Add static qualifier"

This reverts commit cd593cbc446f7caed41dcaf66db88d1c921e6501.

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