[Development] Updated high-DPI support for Qt 5.14

[Paul Tvete]

On Friday, 13 September 2019 17:14:32 CEST Thiago Macieira wrote:

> What happened to QT_AUTO_SCREEN_SCALE_FACTOR and QT_SCREEN_SCALE_FACTORS?

QT_AUTO_SCREEN_SCALE_FACTOR was deprecated in 2016. The recommended 
replacement is QT_ENABLE_HIGHDPI_SCALING. 

It looks like QT_SCREEN_SCALE_FACTORS was briefly broken, but I see there was 
a fix by David Faure that was merged last week: https://codereview.qt-project.org/c/qt/qtbase/+/273182

- Paul