Add support for sys/pwr/fail and sys/key/ctrlaltdel conditions

This patch drops the default signal handlers for SIGPWR and SIGINT with
optional tasks in /etc/finit.conf, triggered by two new conditions:
sys/pwr/fail and sys/key/ctrlaltdel, respectively.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

contrib/finit.conf

@@ -35,6 +35,14 @@ tty /dev/tty1
 tty /dev/tty2
 tty /dev/tty3
 
+# Task to run if ctrl-alt-del is pressed.  This condition is asserted by
+# Finit upon receiving SIGINT (from the kernel).
+task <sys/key/ctrlaltdel> [12345789] initctl reboot -- Rebooting system
+
+# Task to run if the kernel gets a power fail condition is pressed.
+# Asserted by Finit upon receiving SIGPWR (from the kernel).
+task <sys/pwr/fail> [12345789] initctl poweroff -- Shutting down system
+
 # Alternative method instead of runparts
 #task [S] /etc/init.d/keyboard-setup start -- Setting up preliminary keymap
 #task [S] /etc/init.d/acpid start          -- Starting ACPI Daemon