databases/mysqldump-secure: update to 0.16.5

Remove man page's compression, done by port system.
Switch to DISTVERSION.
Pet portlint, portfmt.

Changelog:
https://github.com/cytopia/mysqldump-secure/blob/master/CHANGELOG.md

PR: 276234
Approved by: Jesse Smith <jsmith@resonatingmedia.com> (maintainer)