Remove code that sets user.* system properties.

This has been disallowed by the SELinux for several years now,
so can safely be removed. Given that saveLocaleLocked is
simplified quite a bit, we can now inline into its only caller.

bug: 18910417

(cherry picked from commit 70e8f660)

Change-Id: Ib2888ea22ffca6f4b402efd5780f89c924cd1570