Security update for mgetty (important)

This update for mgetty fixes the following issues:

• CVE-2018-16741: The function do_activate() did not properly sanitize
  shell metacharacters to prevent command injection (bsc#1108752).
• CVE-2018-16745: The mail_to parameter was not sanitized, leading to a
  buffer
  overflow if long untrusted input reached it (bsc#1108756).
• CVE-2018-16744: The mail_to parameter was not sanitized, leading to
  command injection if untrusted input reached reach it (bsc#1108757).
• CVE-2018-16742: Prevent stack-based buffer overflow that could have been
  triggered via a command-line parameter (bsc#1108762).
• CVE-2018-16743: The command-line parameter username wsa passed
  unsanitized to strcpy(), which could have caused a stack-based buffer
  overflow (bsc#1108761).

This update was imported from the SUSE:SLE-15:Update update project.