new port: databases/mysqldump-secure

Mysqldump-secure is a POSIX compliant open-source backup tool for MySQL databases with strong security in mind. It will backup every available database (which is readable by the specified user) as a separate file with the possibility to opt out via blacklisting.

PR: 208032
Submitted by: jsmith@resonatingmedia.com
Reviewed by: matthew
Approved by: matthew (mentor)
Differential Revision: https://reviews.freebsd.org/D9001