Fix unused variable warnings

Libs/DICOM/Core/ctkDICOMModel.cpp

@@ -780,7 +780,9 @@ bool ctkDICOMModel::setChildData(const QModelIndex &index, const QVariant &value
 //------------------------------------------------------------------------------
 bool ctkDICOMModel::setParentData(const QModelIndex &index, const QVariant &value, int role)
 {
+#ifdef CHECKABLE_COLUMNS
   Q_D(const ctkDICOMModel);
+#endif
 
   if(!index.isValid()){
     return false;

Libs/DICOM/Widgets/ctkDICOMBrowser.cpp

@@ -442,7 +442,6 @@ void ctkDICOMBrowser::openQueryDialog()
 //----------------------------------------------------------------------------
 void ctkDICOMBrowser::onQueryRetrieveFinished()
 {
-  Q_D(ctkDICOMBrowser);
   emit this->queryRetrieveFinished();
 }
 

Libs/Visualization/VTK/Widgets/ctkVTKSliceView.cpp

@@ -234,7 +234,6 @@ void ctkVTKSliceView::setColorWindow(double newColorWindow)
 //----------------------------------------------------------------------------
 bool ctkVTKSliceView::eventFilter(QObject *object, QEvent *event)
 {
-  Q_D(ctkVTKSliceView);
   if (object == this->VTKWidget())
     {
     if (event->type() == QEvent::Resize)