Force any experimental SELinux domains (ones tagged with
"permissive_or_unconfined") into unconfined. This flag is
intended to be flipped when we're preparing a release,
to eliminate inconsistencies between user and userdebug devices,
and to ensure that we're enforcing a minimal set of rules for all
SELinux domains.

Without this change, our user builds will behave differently than
userdebug builds, complicating testing.

Change-Id: Ia43d185638336e545a7556c3a0ddf0f34e053706