Remove unused member QFactoryLoaderPrivate::keyList.

Task-number: QTBUG-31476

Change-Id: Ife9b25ede67837152d94cd500a1d7c6dc6cd8ab8
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
QFactoryLoader: Release unused libraries.

Task-number: QTBUG-31476

Change-Id: Ib2eb076afaa21ab1fdc12944f80483e3de260d4b
Reviewed-by: Lars Knoll <lars.knoll@digia.com>