If the cached font has a different DPI than the one used in
QPainter, we need to treat this the same as if other font
properties have changed and redo the layout.
This happened when running the QStaticText test on Wayland,
because the default dpi was 100 and the QPixmap we ended up
drawing to was 96. This caused the pixel size of the font to
be calculated differently when doing drawText() (using 96 dpi)
and drawStaticText() (using the cached 100 dpi).
Pick-to: 6.4
Fixes: QTBUG-100982
Change-Id: Ie4270341bb8a64b6458eb67ba460a282c65dc26b
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
ade2df4c4b