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/llkd.te b/private/llkd.te
index 3f84eb6..385f930 100644
--- a/private/llkd.te
+++ b/private/llkd.te
@@ -22,6 +22,7 @@
 userdebug_or_eng(`
   allow llkd {
     domain
+    -apexd
     -kernel
     -keystore
     -init