D25708: Don't use nullptr to flags

[Laurent Montel]

mlaurent added a reviewer: romangg.

REPOSITORY
  R127 KWayland

REVISION DETAIL
  https://phabricator.kde.org/D25708

To: mlaurent, romangg
Cc: kde-frameworks-devel, LeGast00n, GB_2, michaelh, ngraham, bruns