Import dhcpcd-5.2.12 with the following changes:
* 20-resolv.conf now uses the correct variable for $IF_METRIC
* Compiles on RedHat9
* Exclude interface values when dumping the lease
* Parse static value subnet_mask when it exists instead of deriving from
  ip address
* logger calls now resemble dhcpcd calls to syslog(3)
* Reject offered IP address if INADDR_BROADCAST or INADDR_ANY
* Change the route if source address has changed
* Handle partial UDP checksums so we work in Xen domU
  Thanks to Marius Tomaschewski <mt@suse.de>
* Note the address we are requesting in the broadcast log entry
* When operating on one interface, respect the timeout for in dhcpcd.conf
* Escape | and & characters before passing the value to the shell
  Ensure we set a valid hostname, DNS domain and NIS domain.
  Document the need for input validation in dhcpcd-run-hooks(8).
  Fixes CVE-2011-996
  Based on a patch to dhcpcd-3 by Marius Tomaschewski <mt@suse.de>

(roy)