databases/automysqlbackup: Add the port to the tree
AutoMySQLBackup is a script that takes the pain out of setting up automated
incremental daily, weekly, and monthly backups of MySQL databases.

Submitted by: Christian Schwarz <me@cschwarz.com>
Reviewed by: matthew
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D19612