android_os_SELinux : Use empty array to instead of NULL to avoid the DevicePolicyManagerService cannot start when the SELinux is disabled.

                     Error log
                     07-24 10:32:14.408 F/SystemServer( 1676): BOOT FAILURE making Device Policy Service ready
                     07-24 10:32:14.408 F/SystemServer( 1676): java.lang.NullPointerException
                     07-24 10:32:14.408 F/SystemServer( 1676): 	at com.android.server.zh(DevicePolicyManagerService.java:2628)
                     07-24 10:32:14.408 F/SystemServer( 1676): 	at com.android.server.DevicePolicyManagerService.systemReady(DevicePolicyManagerService.java:1251)
                     07-24 10:32:14.408 F/SystemServer( 1676): 	at com.android.server.ServerThread.run(SystemServer.java:941)

                     Patch Set 2: Append the error log.

Change-Id: I31be031c356ef8e293de0395feefb34ced628341