sepolicy: add rules for updater and update_engine

* We need special exceptions for update_engine scripts because we
  handle backuptool operations through it.

* priv_app needs to be able to make ota package dirs in order to
  put the ota in the correct spot.

Change-Id: I39d9d43ea4eb9e567c6ee24a4cd4f8969cd2bcdd
diff --git a/sepolicy/private/rootfs.te b/sepolicy/private/rootfs.te
new file mode 100644
index 0000000..7cfb964
--- /dev/null
+++ b/sepolicy/private/rootfs.te
@@ -0,0 +1 @@
+allow rootfs labeledfs:filesystem associate;