Allow update_engine to use Binder IPC.

Register service with servicemanager and name the context.

avc: denied { call } for scontext=u:r:update_engine:s0 tcontext=u:r:servicemanager:s0 tclass=binder
avc: denied { add } for service=android.os.IUpdateEngine scontext=u:r:update_engine:s0 tcontext=u:object_r:update_engine_service:s0 tclass=service_manager

Also allow priv_app to communicate with update_engine.

avc: denied { find } for service=android.os.IUpdateEngine scontext=u:r:priv_app:s0:c512,c768 tcontext=u:object_r:update_engine_service:s0 tclass=service_manager
avc: denied { call } for scontext=u:r:priv_app:s0:c512,c768 tcontext=u:r:update_engine:s0 tclass=binder
avc: denied { call } for scontext=u:r:update_engine:s0 tcontext=u:r:priv_app:s0 tclass=binder

Change-Id: Ib4498717c1a72f5faab5ea04c636924ee4eb412c
diff --git a/service_contexts b/service_contexts
index 85dcd3d..4116383 100644
--- a/service_contexts
+++ b/service_contexts
@@ -2,6 +2,7 @@
 account                                   u:object_r:account_service:s0
 activity                                  u:object_r:activity_service:s0
 alarm                                     u:object_r:alarm_service:s0
+android.os.IUpdateEngine                  u:object_r:update_engine_service:s0
 android.security.keystore                 u:object_r:keystore_service:s0
 android.service.gatekeeper.IGateKeeperService    u:object_r:gatekeeper_service:s0
 appops                                    u:object_r:appops_service:s0