warn user of .newsrc.eld when failing gnus install

While the gnus maintainer is now hopefully making the gnus package installable even on my system, I would recommend that if installation fails, there be a messages emitted to see http://groups.google.com/groups?selm=u1y713qu2.fsf%40sdm.de wherein we are told to manually delete the line "(setq gnus-

even official gnus can't be built with debian emacs

One even gets http://debian.linux.org.tw/debian/pool/main/g/gnus/gnus_5.10.2.orig.tar.gz and follows the instructions $ make cd lisp && make EMACS="emacs" lispdir="/usr/share/emacs/site-lisp" all make[1]: Entering directory `/home/jidanni/tmp/gnus-5.10.2/lisp' rm -f *.elc gnus-load.el URLDIR=/usr/