This patch adds a simple but effective watchdog daemon with support for
handover to an external daemon, should one register using the API.
Disabled by default, enable by:
configure --enable-watchdog
The watchdog forks to the background, opening /dev/watchdog setting a
three second timeout, and kicking every second. At shutdown/reboot the
daemon will receive SIGPWR from Finit to exit and cause a WDT reboot.
Signed-off-by: Joachim Nilsson <troglobit@gmail.com>