Script to tar up an already instaled package.

The Script has still a problem, as the MTREE file is removed after
a pkg_add/make install. As leaving the MTREE file will lead to a
~10% increase in space needed for /var/db/pkg which I'm not sure
we should do, esp. as the files are almost always the same again.
(On my notebook with ~250 installed pkgs, the size increasement
would be from 8.8MB to 10MB).

Author:	Hubert Feyrer <hubert@feyrer.de>
WWW:	http://cvsweb.netbsd.org/bsdweb.cgi/pkgsrc/pkgtools/pkg_tarup/