dhcp: bump to version 4.1-ESV-R9

Also install the SysV initscripts from the proper hook.
Since the scripts check for the proper files to be present there's no
need to exclude them according to options since they won't try to start
anything.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>