Add missing interpolator for unsigned int.

Note that there are also some missing interpolators for char, short,
long long etc, but those are most likely less common than unsigned int.

Task-number: QTBUG-33268

Reviewed-by: J-P Nurmi <jpnurmi@digia.com>
(cherry picked from qtbase/09da1f7d1f04f51eca4dc11add2854355fad6cd4)

Change-Id: Ieae8c5f66dab0f997522ea7e7990485ecde33e27
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>