pkgbase: Create a FreeBSD-ftpd package

And put ftpd into it.

MFC after: 2 weeks
Sponsored by: Beckhoff Automation GmbH & Co. KG
Differential Revision: https://reviews.freebsd.org/D33453

(cherry picked from commit 20cd6e315e05a76ee0b745a029ebfd4a79d98e55)