Clean this up, and be more consistent:

Clean this up, and be more consistent:
* Have 'fake' options for all offensive fortune files (fortunes2-o and
  limerick moved to fortunes2-o.real and limerick.real via repository copy).
* build all offensive fortune data files, etc., in the same way.
* Have installation of offensive fortunes controlled by one make variable.
  To disable build/install of offensive fortunes, set
  INSTALL_OFFENSIVE_FORTUNES to anything other than "YES" on the make
  command line, in bsd.own.mk, or in /etc/mk.conf or your ${MAKECONF} file.
  (If changing the setting, you should 'make clean' here and rebuild
  the fortunes before installing.)
* Don't use variables that bsd.prog.mk thinks have certain meanings.