Import dhcpcd-6.11.4 with the following changes:
  *  Fixed octal and hex string parsing in options.
  *  Ignore bogus RTM_DELADDR on FreeBSD when the interface goes down.
  *  Several statically sized buffers have been removed and replaced
    with dynamically sized ones where we have no real idea of what
    the size will be.
  *  Reverse IPv4 route removal order.
  *  Improved handling of Netlink messages on Linux.
  *  Poll for tentative link-local addresses if needed.
  *  Added --small configure directive to reduce binary size
  *  Allow DHCPv6, IPv4lL and authentication to be compiled out
  *  dhcpcd requries the interface to be up when considering link status
  *  Add support for ifa_addrflags in getifaddrs(3)
  *  Add support for ifam_addrflags and ifam_pid from route(4)
  *  If T1 or T2 are not set in DHCPv6 messages, use a default from the
    lowest pltime instead of the expiration time.
  *  Validate lease before moving to REQUEST when both ends use
    rapid commit.
  *  If lease validation fails, don't restart the DISCOVER phase if
    we're already in it.

(roy)