init: allow system UID to setenforce and set booleans

Allow system UID to setenforce and set booleans for SELinux.
Boolean ownerships must also be reset upon policy reload as
the boolean files in selinuxfs are regenerated to match the new policy.

Signed-off-by: Humberto Borba <humberos@gmail.com>
Change-Id: I0dae393892753b4745e6c956289196338bf771d5
Merge "init: allow system UID to setenforce and set booleans" into android-4.4