ahcpd: update to 0.51, fix scripts

ahcpd: update to 0.51, fix scripts

- Full-featured UCI configuration file (including server mode).
- Client mode configuration in /etc/config/network (proto ahcp).
- Launch at most one instance in server/forwarder mode, and as many
  instance as interfaces in client mode.
- Add status and reload options to init script.
- Make /etc/config/ahcpd a config file, simplify Makefile.
- Do not check the pid file (useless).
- 29 January 2010: ahcpd 0.51
  * Servers are now configured with a plain-text configuration file.
  * Implemented client-side support for prefix delegation (-P).
  * Made requesting state more persistent, to deal with packet loss.
  * Fixed a typo that prevented the -I option from working.
  * Fixed compilation on BSD systems.
  * Fixed a bug that could cause an expired lease to be discarded when
    older ones are available.

Signed-off-by: Gabriel Kerneis <kerneis@pps.jussieu.fr>
SVN-Revision: 19813