Update 1.8.18 --> 1.8.18p1

From the sudo announcment:

Depending on your sudoers file configuration, the bug fixed in
1.8.18p1 may have a security impact. For more information, see
https://www.sudo.ws/alerts/noexec_wordexp.html

Approved by: garga@ (maintainer)
MFH: 2016Q4
Differential Revision: D8363