have it be automatically included by bsd.pkg.mk if USE_PKGINSTALL is set
to "YES". This enforces the requirement that bsd.pkg.install.mk be
included at the end of a package Makefile. Idea suggested by Julio M.
Merino Vidal <jmmv at menta.net>.
* rox-base now owns share/rox and libexec/rox directories;
* rox-base now installs in share/rox for consistency;
* change information about CHOICESPATH in MESSAGE;
* bump to nb1.