Import dhcpcd-6.4.4 with the following changes:
  *  Many bounds checking fixes from Tobias Stoeckmann
  *  Improve error when the authentication token cannot be found
  *  close the IPv4 specific UDP socket when done sending
  *  Implemented a write queue to the control sockets
  *  Only send interfaces to control sockets when in a BOUND state
  *  Add a sample controlgroup directive to dhcpcd.conf to make setup easier
  *  Add variables if_oneup and if_ipwaited so hook scripts know the overall
     state of dhcpcd better
  *  Pass RC_SVCNAME from enviromment to hooks so that a service hook can
     know it's name (may not be dhcpcd)
  *  Document every variable set for dhcpcd-run-hooks(8)
  *  Allow SSIDs with non printable characters to be used in ssid selection
     in dhcpcd.conf
  *  Add an unprivileged control socket so that normal users can obtain
     dhcpcd running state