D26320: endl is Qt:: namespaced in qt5.15. Port to \n and flush when QTextStream is not on a QFile

[Laurent Montel]

mlaurent added a reviewer: dfaure.

REPOSITORY
  R269 BluezQt

REVISION DETAIL
  https://phabricator.kde.org/D26320

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