Add options SYSCF (to add a system-wide configuration file) and SYSCF_FILE
(for a file-based implementation of SYSCF) - this allows a binary distribution
to be configured at install time. The only option supported at this time is
WIZARDS - a list of usernames which can use -D; currently only for unix-likes
but should be extendable to anything that has a concept of multiple users.
Add mac tty multiuser config using sgid.
