Don't use plugin from libs/qmljs.

Change-Id: Ia345c567cd1f244ab2191017810ef3eeb91fe0e4
Reviewed-on: http://codereview.qt.nokia.com/213


Reviewed-by: Roberto Raggi <roberto.raggi@nokia.com>
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>