Add policy for apexd.

apexd is a new daemon for managing APEX packages installed
on the device. It hosts a single binder service, "apexservice".

Bug: 112455435
Test: builds, binder service can be registered,
      apexes can be accessed, verified and mounted
Change-Id: I634ad100f10b2edcd9a9c0df0d33896fa5d4ed97
diff --git a/private/atrace.te b/private/atrace.te
index 2a7ccd0..37e9702 100644
--- a/private/atrace.te
+++ b/private/atrace.te
@@ -31,6 +31,7 @@
 
 allow atrace {
   service_manager_type
+  -apex_service
   -incident_service
   -netd_service
   -stats_service