Partially reverts 4f077b7e5f.
Can't overload with forwarding references and lvalue references. Use a single
forwarding reference overload, but take care of not trying to create a
QScopeGuard of reference type and forward instead of moving.
Add tests to ensure calling with both lvalues and rvalues is possible.
Change-Id: Ia034afe0a8feb08246c2c7c154a85cae37421c98
Reviewed-by: Ville Voutilainen <ville.voutilainen@qt.io>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>