Add persistent property for SELinux enforcment status.

Also adds triggers for going between enforcing and
permissive status.

Bug: 8702843
Change-Id: I841d80999b96acf6b6fd0a5408fb074952d6ae72

init/property_service.c

@@ -91,6 +91,7 @@ struct {
     { "persist.service.", AID_SYSTEM,   0 },
     { "persist.security.", AID_SYSTEM,   0 },
     { "persist.service.bdroid.", AID_BLUETOOTH,   0 },
+    { "persist.selinux.enforcing", AID_SYSTEM,  0},
     { "selinux."         , AID_SYSTEM,   0 },
     { NULL, 0, 0 }
 };

rootdir/init.rc

@@ -409,6 +409,12 @@ on property:selinux.reload_policy=1
     restart ueventd
     restart installd
 
+on property:persist.selinux.enforcing=1
+    setenforce 1
+
+on property:persist.selinux.enforcing=0
+    setenforce 0
+
 service console /system/bin/sh
     class core
     console