The change 35bc3dc45a moved some padding out
of QTextureGlyphCache into the font engines directly, however this was not
done for the DirectWrite font engine so it caused a buffer overrun.
Task-number: QTBUG-41782
Change-Id: I4e643159036f06c5edd8a742dc6694d517a47826
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@theqtcompany.com>