COMP: Fix -fpermissive error in OptimizingInterpolationDisplacementCa…

…lculator

This commit fixes the following error reported when building
SlicerITKUltrasound extension againg Slicer 4.13 and ITK 5.3:

  In file included from /path/to/SlicerITKUltrasound-Release/ITKUltrasound/include/itkBlockMatchingOptimizingInterpolationDisplacementCalculator.h:202,
                   from /path/to/SlicerITKUltrasound-Release/ITKUltrasound/include/itkBlockMatchingDisplacementPipeline.h:39,
                   from /path/to/SlicerITKUltrasound/GenerateDisplacementFromFrames/GenerateDisplacementFromFrames.cxx:25:
  /path/to/SlicerITKUltrasound-Release/ITKUltrasound/include/itkBlockMatchingOptimizingInterpolationDisplacementCalculator.hxx: In instantiation of ‘void itk::BlockMatching::OptimizingInterpolationDisplacementCalculator<TMetricImage, TDisplacementImage, TCoordRep>::SetMetricImagePixel(const PointType&, const IndexType&, itk::BlockMatching::OptimizingInterpolationDisplacementCalculator<TMetricImage, TDisplacementImage, TCoordRep>::MetricImageType*) [with TMetricImage = itk::Image<float, 2>; TDisplacementImage = itk::Image<itk::Vector<float, 2>, 2>; TCoordRep = double; itk::BlockMatching::OptimizingInterpolationDisplacementCalculator<TMetricImage, TDisplacementImage, TCoordRep>::PointType = itk::Point<double, 2>; itk::BlockMatching::OptimizingInterpolationDisplacementCalculator<TMetricImage, TDisplacementImage, TCoordRep>::IndexType = itk::Index<2>; itk::BlockMatching::OptimizingInterpolationDisplacementCalculator<TMetricImage, TDisplacementImage, TCoordRep>::MetricImageType = itk::Image<float, 2>]’:
  /path/to/SlicerITKUltrasound-Release/ITKUltrasound/include/itkBlockMatchingOptimizingInterpolationDisplacementCalculator.hxx:41:1:   required from here
  /path/to/SlicerITKUltrasound-Release/ITKUltrasound/include/itkBlockMatchingOptimizingInterpolationDisplacementCalculator.hxx:95:5: error: passing ‘const InterpolatorType’ {aka ‘const itk::InterpolateImageFunction<itk::Image<float, 2>, double>’} as ‘this’ argument discards qualifiers [-fpermissive]
     95 |     m_CostFunction->GetInterpolator()->SetInputImage(metricImage);
        |     ^~~~~~~~~~~~~~
  In file included from /path/to/Slicer-Release/ITK/Modules/Core/ImageFunction/include/itkImageFunction.h:229,
                   from /path/to/Slicer-Release/ITK/Modules/Core/ImageFunction/include/itkInterpolateImageFunction.h:21,
                   from /path/to/Slicer-Release/ITK/Modules/Core/ImageFunction/include/itkWindowedSincInterpolateImageFunction.h:23,
                   from /path/to/SlicerITKUltrasound-Release/ITKUltrasound/include/itkBlockMatchingDisplacementPipeline.h:26,
                   from /path/to/SlicerITKUltrasound/GenerateDisplacementFromFrames/GenerateDisplacementFromFrames.cxx:25:
  /path/to/Slicer-Release/ITK/Modules/Core/ImageFunction/include/itkImageFunction.hxx:57:1: note:   in call to ‘void itk::ImageFunction<TInputImage, TOutput, TCoordRep>::SetInputImage(const InputImageType*) [with TInputImage = itk::Image<float, 2>; TOutput = double; TCoordRep = double; itk::ImageFunction<TInputImage, TOutput, TCoordRep>::InputImageType = itk::Image<float, 2>]’
     57 | ImageFunction<TInputImage, TOutput, TCoordRep>::SetInputImage(const InputImageType * ptr)
        | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

include/itkBlockMatchingOptimizingInterpolationDisplacementCalculator.hxx

@@ -92,7 +92,7 @@ OptimizingInterpolationDisplacementCalculator<TMetricImage, TDisplacementImage,
     for (unsigned int i = 0; i < ImageDimension; i++)
       parameters[i] += 0.1;
     m_CostFunction->Initialize(parameters);
-    m_CostFunction->GetInterpolator()->SetInputImage(metricImage);
+    const_cast<InterpolatorType*>(m_CostFunction->GetInterpolator())->SetInputImage(metricImage);
     m_Optimizer->StartOptimization();
 
     parameters = m_Optimizer->GetCurrentPosition();