The name 'labs' should not appear in officially shipped Qt

The src/imports install in a place that means qml-script writers have to include 'labs' in the thing they import.
This is presumably done to make clear these imports are not officially supported.
As anything shipped inside of Qt will have to be source compatible the name of 'labs' should be removed to make this clear or otherwise we'll have to ship it using the name 'labs' for as long as Qt4 exists.