* Add an optional third field to the sets file which is a list of
comma separated keywords that control if the line is printed.
Currently supported keywords
kerberos4 ${MKKERBEROS4} != no
kerberos ${MKKERBEROS} != no
lint ${MKLINT} != no
obsolete ${obsolete} != 0.
In this case, non obsolete files are not printed.
(This will allow future support for builds with variables such as
MKHESIOD and MKYP set to "no".)
* Use sh(1)'s getopts where appropriate, and otherwise cleanup the
various scripts.
* Move defaults for sets.subr from sets.defaults into sets.subr.
Move replicated code for determining stuff such as shlibs type
from various scripts into sets.subr.
* Merge the obsolete.*, krb.*, krb4.* and lint.* into the appropriate
main lists with the relevant third field keyword(s).
