Log Message:
Import dhcpcd-7.2.0 with the following changes:
  *  build: latest gmake-3 works once more
  *  build: exits on error in a subdir
  *  BSD: PF_LINK sockets now closed when no longer needed
  *  BSD: Fix detecting interface for scoped routes
  *  Solaris: Many, many, many fixes - pretty much works now
  *  script: Allow "" to mean /dev/null
  *  script: Add static routers and routes to env
  *  DHCP: outbound interface is no longer dictated with IP_PKTINFO
  *  DHCP: BPF sockets now closed when no longer needed
  *  DHCPv6: Allow nooption dhcp6_unicast to work
  *  DHCPv6: Don't spam syslog if we always get the same error
  *  route: Log pid which deleted routes of interest