More changes went into oc-dev after the freeze-date.  Reflect them.
(cherry-pick of commit: 148578a6)

Bug: 37916906
Bug: 37896931
Test: prebuilts - none.
Change-Id: I3300751ea7362d5d96b327138544be65eb9fc483

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

Copy the final system sepolicy from oc-dev to its prebuilt dir
corresponding to its version (26.0) so that we can uprev policy and
start maintaining compatibility files, as well as use it for CTS
tests targeting future platforms.

(cherry-pick of commit: 5c6a227e)

Bug: 37896931
Bug: 37916906
Test: none, this just copies the old policy.
Change-Id: Ib069d505e42595c467e5d1164fb16fcb0286ab93