This patch drops the stand-alone reboot binary and folds it into the
initctl tool, which now becomes a multi-call binary.
With this change the reboot/shutdown/poweroff/halt/suspend commands also
no longer default to sending signals to PID 1, instead it now uses the
initctl <--> finit UNIX domain socket API. Signals are only used as a
fallback in case of non-working domain socket. The -f,--force mode of
operation still works, where `reboot(2)` is called directly.
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>