Fix unused variable warnings

Libs/DICOM/Widgets/ctkDICOMQueryRetrieveWidget.cpp

@@ -438,7 +438,7 @@ void ctkDICOMQueryRetrieveWidget::onSelectionChanged(const QItemSelection &selec
 {
   Q_UNUSED(selected);
   Q_UNUSED(deselected);
-  Q_D(ctkDICOMQueryRetrieveWidget);
+  //Q_D(ctkDICOMQueryRetrieveWidget);
 
   logger.debug("Selection change");
   // TODO: allow selection of individual studies to retrieve.  Requires

Libs/Widgets/ctkSliderWidget.cpp

@@ -127,6 +127,7 @@ int ctkSliderWidgetPrivate::synchronizedSpinBoxWidth()const
 // --------------------------------------------------------------------------
 void ctkSliderWidgetPrivate::synchronizeSiblingWidth(int width)
 {
+  Q_UNUSED(width);
   Q_Q(const ctkSliderWidget);
   QList<ctkSliderWidget*> siblings =
     q->parent()->findChildren<ctkSliderWidget*>();
@@ -144,6 +145,7 @@ void ctkSliderWidgetPrivate::synchronizeSiblingWidth(int width)
 // --------------------------------------------------------------------------
 void ctkSliderWidgetPrivate::synchronizeSiblingDecimals(int decimals)
 {
+  Q_UNUSED(decimals);
   Q_Q(const ctkSliderWidget);
   QList<ctkSliderWidget*> siblings =
     q->parent()->findChildren<ctkSliderWidget*>();