Set the default shutdown timeout to 5s.

When shutting down, allow services to exit cleanly by sending them a
SIGTERM signal and waiting 5 seconds before rebooting.

Bug: 26216447
Test: manual: `power_example --action=shut_down`. All services exit
cleanly then the system reboots.

Change-Id: I4c1c0e42ce9d0ca86381c790f2d28d22f2bb06e9
1 file changed