Log Message:
Import dhcpcd-6.11.3 with the following changes:
  *  Workaround a 14 year old BSD issue where initial address lifetimes
     are transfered to the prefix route and are not updated again,
     causing the kernel to remove the route.
     The fix is to initially add the address with infinite lifetimes
     and then change the lifetimes to the correct ones.
  *  IPv6 RA routes are now expired by dhcpcd.
  *  Fix gateway interface assignment on BSD.
  *  Only mask off signals we do something with
     (allows coredumps on some platforms)
  *  Fix a memory issue where an old lease could be read and discarded
     but the buffer length not reset.
  *  Bind DHCPv6 to the link-local address when not running in master
     mode so that many dhcpcd instances can run per interface.