debugger: workaround for shadowed items in locals view

The "<shadowed x>" space caused trouble on parameter passing.
As workaround, don't produce any.

Change-Id: Ibef1bfc8dc43c790ac2a2aeb52d3509347b6c997
Reviewed-on: http://codereview.qt.nokia.com/1068


Reviewed-by: hjk <qthjk@ovi.com>