Call updateAccessibility with the right index.

Call updateAccessibility with the right index.

In Qt 4 index 0 was the widget itself.
With the cleanup of child index this now changed.
The default constructor uses -1 as parameter to signify that
the widget is the cause, not a child.

Change-Id: I329a1cc91bf2d1d1d8534739acbddfe107f40364
Reviewed-by: Jan-Arve Sæther <jan-arve.saether@nokia.com>