This CL changes the ENABLE_CFI flag to default to enabled. Setting it
to false will override local settings to enable CFI.
Bug: 30227045
Bug: 22033465
Test: m -j40 works and device boots
Test: cfi is honored unless the global flag is set.
Change-Id: Ie3285c5eac60c8f6012c6b6c23be149a8787af0c