new ports: databases/mantis

Mantis is a web-based bugtracking system.

It is written in the PHP scripting language and requires
the MySQL database and a webserver. Mantis has been installed
on Windows, MacOS, OS/2, and a variety of Unix operating
systems. Any web browser should be able to function as a
client. It is released under the terms of the GNU General
Public License (GPL).

PR: ports/46034
Submitted by: Sebastien Gioria <gioria@FreeBSD.ORG>