BUG: mantis 1504 - use implicite conversion of SmartPointer to const pointer

Modules/Core/Transform/include/otbStreamingWarpImageFilter.txx

@@ -304,15 +304,12 @@ StreamingWarpImageFilter<TInputImage, TOutputImage, TDisplacementField>
   const PixelType paddingValue = this->GetEdgePaddingValue();
   OutputImagePointerType outputPtr = this->GetOutput();
 
-  // ITK 4.13 fix const correctness of GetDisplacementField. Use ITK version
-  // number for backward compatibility
+  // ITK 4.13 fix const correctness of GetDisplacementField. 
   // Related commit in ITK: https://github.com/InsightSoftwareConsortium/ITK/commit/0070848b91baf69f04893bc3ce85bcf110c3c63a
   
-  #if (ITK_VERSION_MAJOR >= 4 && ITK_VERSION_MINOR >= 13)
+  // DisplacementFieldPointerType fieldPtr = this->GetDisplacementField();
   const DisplacementFieldType * fieldPtr = this->GetDisplacementField();
-  #else
-  DisplacementFieldPointerType fieldPtr = this->GetDisplacementField();
-  #endif
+
 
   DisplacementFieldRegionType defRegion = fieldPtr->GetLargestPossibleRegion();