This commit add support for ctrld to run on freebsd, supported platforms
are amd64/arm64/armv6/armv7,386.
Supporting freebsd also requires adding debian and openresolv resolvconf.
Updates #47
For interface managed by systemd-networkd, systemd-resolved can not
reset DNS. To fix this, attempting to check before the run loop and set
the suitable manager for the system.
Updates #55