Do not change ownership on /sys/fs/selinux/enforce.

There is no longer any reason to permit system UID to set enforcing mode.

Change-Id: Ie28beed1ca2b215c71f2847e2390cee1af1713c3
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Merge "Do not change ownership on /sys/fs/selinux/enforce." into kitkat