The excludedirs variable doesn't work correctly when its values have
'../' in them. The solution is to use QDir::cleanPath() on each path
name before using it.

Task Nr: QTBUG-26492

Change-Id: I2db74e79cf096c1c75ab5b10877320360c016fc7
Reviewed-by: Casper van Donderen <casper.vandonderen@nokia.com>