Add policy for the android protected confirmation service.

This is the service offered by Keystore 2.0 to provide APC service to
application. It was formerly part of the IKeystoreService interface.
Not it is an interface in ints own right.

Test: Keystore 2.0 can register the apc service interface.
      Apps can lookup and call this interface.
Bug: 159341464
Change-Id: I058adf0021d9b89f4eac7534e366c29071f0f98b
diff --git a/private/service_contexts b/private/service_contexts
index 91da637..90a85cd 100644
--- a/private/service_contexts
+++ b/private/service_contexts
@@ -20,6 +20,7 @@
 alarm                                     u:object_r:alarm_service:s0
 android.os.UpdateEngineService            u:object_r:update_engine_service:s0
 android.os.UpdateEngineStableService      u:object_r:update_engine_stable_service:s0
+android.security.apc                      u:object_r:apc_service:s0
 android.security.identity                 u:object_r:credstore_service:s0
 android.security.keystore                 u:object_r:keystore_service:s0
 android.service.gatekeeper.IGateKeeperService    u:object_r:gatekeeper_service:s0