Testconfig: Disabling ios stage with QtWebkit-Examples

We are not configuring qtwebkit when building for IOS, so there
is no need to test its examples.

Change-Id: I5e643c118e2880661bd8e4371d3d2621e3f84ed0
Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>
Reviewed-by: Tony Sarajärvi <tony.sarajarvi@digia.com>