Move the responsibility for rebooting the system from the
reboot command to init. Init is in a better position to take
actions to bring the system down cleanly, including making sure
filesystems are mounted read-only.
The only UIDs which can perform an init triggered reboot are
root, system, and shell.
Modify the reboot command so that it calls into init to perform
the reboot. The reboot command no longer requires CAP_SYS_BOOT.
Remove the -n reboot option and code which supports it. Anyone needing
to do an unclean shutdown can just do a 'echo c > /proc/sysrq-trigger'.
Modify adb so that it calls into init to perform a shutdown.
Bug: 8646621
Change-Id: I84c0513acb549720cb0e8c9fcbda0050f5c396f5
ca8e66a8b0