Mark updatable APEXes

Mark updatable APEXes as updatable: true so that they are opted-out from
optimizations that make sense only for non-updatable modules; such as
symlinking to the libs in the system partition.

Bug: 149805758
Test: m and check that there is no symlink from the APEX to the system
partition.

Change-Id: I368d72cc6dba6de38fd18f2479b4a2ce77aa1a69