mail/opensmtpd: Update to 5.9.2

• Update to 5.9.2p1
• Remove usernamelen patch (default 255+1)
• Fix renamed configure args
• Add symlink for makemap (now included in smtpctl)
• Align versioning with other OpenBSD projects
• Add _smtpq group
• Add UPDATING entry for existing installs
• Update pkg-message for existing installs

Reviewed by: adamw, mat
Approved by: adamw, maintainer (implicit)
Differential Revision: D6421