rc: make ctld depend on NETWORKING

This fixes a problem where ctld(8) would refuse to start on boot
with a specific IP address to listen on configured in ctl.conf(5).
It also fixes a problem where ctld(8) would fail to start with
some network interfaces which require a sysctl.conf(5) tweak
to configure them, eg to switch them from InfiniBand to IP mode.

PR: 232397
Reported By: Mahmoud Al-Qudsi <mqudsi at neosmart.net>
Submitted By: Jeremy Faulkner <gldisater at gmail.com>
Reviewed By: mav
Differential Revision: https://reviews.freebsd.org/D29578