Qbs: Clear compile issues on rebuild and remove useless comment

Change-Id: I705564ee422295ec467cd51a62aa71183afa0b63
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>
Qbs: Remove some useless member variables

Change-Id: I648984616ebd965e51ebe6ec6f369a6dfa4fc339
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>