Log Message:
Import dhcpcd-5.1.2 with these changes:
* ClientID is now reported when interface starts
* -w, --wait forces dhcpcd to wait until an interface gets a lease or
  times out
* Ensure DHCP socket is open when sending a DECLINE
* Uses new hwaddr if existing interface is downed and then changed.
* No longer works on firewire interfaces by default.

dhcpcd-5.1.2 has a new behaviour change - when starting up and at least 1
interface has a carrier then it tries to get a lease or times out.
It still daemonises regardless. This, along with the -b and -w flags
allows total control over the desired behaviour of dhcpcd.