Allow the unsupportedappusage-annotation to be used for device variants

Some modules, e.g. libphonenumber-platform, depend on core platform API
solely for accessing the dalvik.annotation.compat.UnsupportedAppUsage
annotation. Building device variants of unsupportedappusage-annotation
will allow those modules to switch to core_current.

Bug: 134379140
Test: m droid
Change-Id: I1634b8ffd2a28c2663defd2a4a4e40d78b174d91