Add keystore user_changed permission

user_changed will be used for state change methods around android user
creation/deletion.

Change-Id: I295ca9adfc4907b5d7bcf0555f6e5a9a3379635b
diff --git a/access_vectors b/access_vectors
index 65b7e22..e79ad1b 100644
--- a/access_vectors
+++ b/access_vectors
@@ -910,6 +910,7 @@
 	sync_uid
 	password_uid
 	add_auth
+	user_changed
 }
 
 class debuggerd