androiddeployqt: always declare features as unrequired.

Features declared by Qt modules are not necessarily used by
an app, so we mark them as unrequired. It's the responsibility
of the developer to mark them as required if needed.

Task-number: QTBUG-36921
Change-Id: Id0de248347d49c119bc9a1c37f4d0882065a1601
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@digia.com>