Add mapping compatibility file for sepolicy api lvl 26.0

commit: 5c6a227e added the oc-dev
sepolicy prebuilts (api 26.0), but did not include the corresponding
base mapping file, which is to be maintained along with current
platform development in order to ensure backwards compatibility.
(cherry-pick of commit: 5e4e0d7f)

Bug: 37916906
Bug: 37896931
Test: none, this just copies the old mapping file to prebuilts.
Change-Id: Ia5c36ddab036352845878178fa9c6a9d649d238f