Support loss accumulation on gpu
Support loss accumulation on gpu

hvy/chainer,ronekko/chainer,elviswf/chainer,muupan/chainer,umitanuki/chainer,hvy/chainer,cemoody/chainer,sou81821/chainer,wavelets/chainer,laysakura/chainer,bayerj/chainer,tigerneil/chainer,hvy/chainer,minhpqn/chainer,muupan/chainer,1986ks/chainer,t-abe/chainer,cupy/cupy,cupy/cupy,wkentaro/chainer,ktnyt/chainer,truongdq/chainer,niboshi/chainer,kikusu/chainer,keisuke-umezawa/chainer,anaruse/chainer,benob/chainer,ysekky/chainer,tereka114/chainer,niboshi/chainer,truongdq/chainer,aonotas/chainer,chainer/chainer,keisuke-umezawa/chainer,woodshop/chainer,hvy/chainer,tkerola/chainer,okuta/chainer,sinhrks/chainer,kuwa32/chainer,jnishi/chainer,jnishi/chainer,okuta/chainer,kashif/chainer,masia02/chainer,kiyukuta/chainer,rezoo/chainer,benob/chainer,wkentaro/chainer,jnishi/chainer,chainer/chainer,niboshi/chainer,keisuke-umezawa/chainer,pfnet/chainer,t-abe/chainer,ktnyt/chainer,hidenori-t/chainer,wkentaro/chainer,Kaisuke5/chainer,kikusu/chainer,keisuke-umezawa/chainer,ytoyama/yans_chainer_hackathon,cupy/cupy,AlpacaDB/chainer,ikasumi/chainer,jfsantos/chainer,chainer/chainer,AlpacaDB/chainer,niboshi/chainer,sinhrks/chainer,okuta/chainer,ktnyt/chainer,ktnyt/chainer,wkentaro/chainer,woodshop/complex-chainer,jnishi/chainer,cupy/cupy,yanweifu/chainer,tscohen/chainer,chainer/chainer,okuta/chainer,delta2323/chainer