Log Message:
Import dhcpcd-5.2.0 with the following changes:
* VendorID is now dhcpcd-$version:$OS-$version:$machine:$platform
* IPv4LL address range can now be used in DHCP requests
* sysctl net.ipv4.conf.$iface.promote_secondaries enabled on Linux
  This resolves a long standing issue of changing ip on the same subnet.
* IPv4LL correctly resets the DHCP timer.