QLCDNumber: remove unused header #include

Change-Id: Ic1608a11a48c373b7ad816c1305cce0fe236425b
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
added QAbstractSpinBox::setGroupSeparatorShown function.

[ChangeLog][QtWidgets][QAbstractSpinBox] QTBUG-5142 - This will
allow a group (thousand) separator to be shown in QSpinBox
and QDoubleSpinBox widgets.

Task-number: QTBUG-5142

Change-Id: I2e23f5f83c93bb092a2dbd784e06d17d40d42909
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>