potential int overflow in qcommonstyle

In qcommonstyle.cpp, at line 4086 we have:

uint range = scrollbar->maximum - scrollbar->minimum;

now, both maximum and minimum are signed integers, giving a risk of overflow if provided values are malformed (negative) and give an unreasonably huge range

encountered that in QtQuickcontrols1 qstyle wrapper where one can set incorrect values from qml and make the app crash