Add policy for property service.
New property_contexts file for property selabel backend.
New property.te file with property type declarations.
New property_service security class and set permission.
Allow rules for setting properties.
diff --git a/security_classes b/security_classes
index 38d78eb..197805e 100644
--- a/security_classes
+++ b/security_classes
@@ -134,4 +134,7 @@
 class binder
 class zygote
 
+# Property service
+class property_service          # userspace
+
 # FLASK