Creator warns about missing qmlviewer for Qt5

Steps to reproduce:

• open Tools->Options->Build & Run->Qt Versions
• configure a new Qt version that is Qt5

Current behaviour:

• a warning sign is displayed to the left of the version
• below the qmake location there's a warning 'No qmlviewer installed.'
• this happens although Qt5 contains qmlviewer and qmlscene inside qtbase/bin