D27910: Make sure warning output is enabled before testing if the correct warning is printed

[Aleix Pol Gonzalez]

apol added a comment.


  Is it passing on the CI because somehow we enable warnings on there?
  
https://build.kde.org/job/Frameworks/job/karchive/job/kf5-qt5%20SUSEQt5.13/60/testReport/

REPOSITORY
  R243 KArchive

REVISION DETAIL
  https://phabricator.kde.org/D27910

To: sandsmark, dfaure
Cc: apol, kde-frameworks-devel, LeGast00n, cblack, GB_2, michaelh, ngraham, 
bruns