Added a comment for Travis CI steps why LAPACK is installed only for Linux
Added a comment for Travis CI steps why LAPACK is installed only for Linux

wkentaro/chainer,wkentaro/chainer,okuta/chainer,okuta/chainer,okuta/chainer,hvy/chainer,niboshi/chainer,chainer/chainer,wkentaro/chainer,chainer/chainer,niboshi/chainer,chainer/chainer,pfnet/chainer,hvy/chainer,okuta/chainer,hvy/chainer,wkentaro/chainer,niboshi/chainer,chainer/chainer,hvy/chainer,niboshi/chainer