Make some files in etc obsolete

Make some files in etc obsolete

These are old copies of online information that is not Emacs-specific.

* etc/CENSORSHIP, etc/GNU, etc/LINUX-GNU, etc/THE-GNU-PROJECT, etc/WHY-FREE:
Replace contents with pointers to www.gnu.org or emacs.info, mark obsolete.

* src/callproc.c (init_callproc): In etc, look for NEWS rather than GNU.

* lisp/startup.el (fancy-startup-text):
* lisp/help.el (describe-gnu-project): Visit online info about GNU project.

* doc/emacs/help.texi (Help Files): Update C-h g description.

* doc/misc/efaq.texi (Informational files for Emacs): Do not mention etc/GNU.

* admin/notes/copyright: Remove references to these files.

* etc/MACHINES, etc/NEWS.19: Replace references to these files.