D9029: Fix creating a directory via KNewFileMenu+KIO::mkpath on Qt 5.9.3+

[Eike Hein]

hein added a reviewer: Frameworks.

REPOSITORY
  R241 KIO

REVISION DETAIL
  https://phabricator.kde.org/D9029

To: hein, dfaure, thiago, elvisangelaccio, #frameworks
Cc: #frameworks