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.

Exempt-From-Owner-Approval: cherry-pick from internal

Merged-In: Idb55300a60a261c7bb6359439ed220ff51fcf06c
(cherry picked from commit 8201bdfa)
Change-Id: Idb55300a60a261c7bb6359439ed220ff51fcf06c