various cmake improvements/debug
various cmake improvements/debug

apaszke/cunn,colesbury/cunn,szagoruyko/cunn,colesbury/cunn,jonathantompson/cunn,andreaskoepf/cunn,fmassa/cunn,colesbury/cunn,jonathantompson/cunn,ml-lab/cunn,soumith/cunnsparse,lukasc-ch/cunn,apaszke/cunn,Aysegul/cunn,lukasc-ch/cunn,Saulzar/cunn,jhjin/cunn,szagoruyko/cunn,jhjin/cunn,ominux/cunn,danielsig727/cunn,apaszke/cunn,albanD/cunn,clementfarabet/cunn,clementfarabet/cunn,rotmanmi/cunn,davidBelanger/cunn,hughperkins/cunn,andreaskoepf/cunn,rotmanmi/cunn,davidBelanger/cunn