fix to skip GPU tests on AppVeyor
fix to skip GPU tests on AppVeyor

chainer/chainer,anaruse/chainer,chainer/chainer,rezoo/chainer,jnishi/chainer,jnishi/chainer,okuta/chainer,jnishi/chainer,ktnyt/chainer,keisuke-umezawa/chainer,okuta/chainer,aonotas/chainer,chainer/chainer,ktnyt/chainer,ronekko/chainer,hvy/chainer,tkerola/chainer,keisuke-umezawa/chainer,chainer/chainer,wkentaro/chainer,keisuke-umezawa/chainer,ktnyt/chainer,niboshi/chainer,wkentaro/chainer,niboshi/chainer,niboshi/chainer,hvy/chainer,wkentaro/chainer,okuta/chainer,niboshi/chainer,hvy/chainer,hvy/chainer,ktnyt/chainer,pfnet/chainer,jnishi/chainer,keisuke-umezawa/chainer,wkentaro/chainer,okuta/chainer