Hopefully supress dashboard compiler warning in QT header

Suppression used since we can't change QT itself easily:

In file included from /Users/kitware/Dashboards/My Tests/Nightly/VTK/build-gcc/GUISupport/Qt/moc_Q4VTKWidgetPlugin.cxx:10:
In file included from /Users/kitware/Dashboards/My Tests/Nightly/VTK/build-gcc/GUISupport/Qt/../../../source/GUISupport/Qt/Q4VTKWidgetPlugin.h:28:
In file included from /Users/kitware/Dashboards/Support/Qt-4.8.0/include/QtDesigner/QDesignerCustomWidgetInterface:1:
In file included from /Users/kitware/Dashboards/Support/Qt-4.8.0/include/QtDesigner/customwidget.h:45:
/Users/kitware/Dashboards/Support/Qt-4.8.0/lib/QtDesigner.framework/Headers/extension.h:94:50: warning: unused parameter 'manager' [-Wunused-parameter]
inline T qt_extension(QAbstractExtensionManager* manager, QObject *object)
                                                 ^
/Users/kitware/Dashboards/Support/Qt-4.8.0/lib/QtDesigner.framework/Headers/extension.h:94:68: warning: unused parameter 'object' [-Wunused-parameter]
inline T qt_extension(QAbstractExtensionManager* manager, QObject *object)
                                                                   ^

Change-Id: Ia645327ecffe1ef06e5d4349d01dd5da80ecf295
Merge topic 'suppress-unused-params' into master

fd385ce8 Hopefully supress dashboard compiler warning in QT header