Fix font cache check in QFontEngineFT::recalcAdvances()

Cached font was used regardless of the format, resulting in incorrect
advance in some cases when default format differed from the cached
format.

Task-number: QTBUG-24188
Change-Id: I39e4156bd9ba743afa7e106e934c90227fbf2b8b
Reviewed-by: Jiang Jiang <jiang.jiang@nokia.com>
(cherry picked from qtbase/2ea976c3a713535c2419d936d575e0b24545f0fa)
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@digia.com>
Reviewed-by: Lisandro Damián Nicanor Pérez Meyer <perezmeyer@gmail.com>
Reviewed-by: Jiang Jiang <gzjjgod@gmail.com>
QListView: Catch stack overflow on mutual scrollbar calculation.

Backport of fc4993be1fa7673016b6e5d81134463f163051f6 from Qt 5.

Task-number: QTBUG-39902
Task-number: QTBUG-38517
Change-Id: I66b2c7304423dd65d67158ae0dc70ad12e4fa783
Reviewed-by: Christoph Schleifenbaum <christoph.schleifenbaum@kdab.com>
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>