qt: Stop the effect of hidden widgets on the size of QStackedWidget
qt: Stop the effect of hidden widgets on the size of QStackedWidget

Layouts of the hidden widgets, those are children of QStackedWidget,
could prevent to adjust the size of the parent widget in the
WalletFrame widget.

Github-Pull: bitcoin-core/gui#176
Rebased-From: af58f5b12cea91467692dd4ae71d8cc916a608ed

qtumproject/qtum,litecoin-project/litecoin,qtumproject/qtum,rnicoll/dogecoin,rnicoll/dogecoin,litecoin-project/litecoin,qtumproject/qtum,qtumproject/qtum,rnicoll/dogecoin,qtumproject/qtum,litecoin-project/litecoin,litecoin-project/litecoin,litecoin-project/litecoin,qtumproject/qtum,litecoin-project/litecoin,rnicoll/dogecoin,qtumproject/qtum,rnicoll/dogecoin