Update status for CVE-2019-18862/mailutils

The utility actually should have been setuid:

   * The maidag utility is withdrawn

   The main purpose of this utility was to work as local mail delivery
   agent (MDA), a program responsible for final delivery of email
   messages to the recipient's mailbox. As such it required suid
   privileges.

As in every suite the binary is not installed setuid, consider it unimportant
making it a non-issue for the privilege escalation.