Compatibility with clang-19

[mvieth]

Fix errors reported by the upcoming clang 19. It seems like clang 19 checks these functions, even though they are not actually compiled/used anywhere (otherwise the other compilers would have complained already).
Regarding the changes in poisson4: I did my best to put something plausible there, but I am not very familiar with that code, so it might not be the best solution. But since those function are seemingly not used anywhere, it should not matter that much.

Here are the errors reported by clang 19:

In file included from /pcl/surface/src/poisson.cpp:40:
In file included from /pcl/surface/include/pcl/surface/impl/poisson.hpp:48:
In file included from /pcl/surface/include/pcl/surface/3rdparty/poisson4/octree_poisson.h:283:
/pcl/surface/include/pcl/surface/3rdparty/poisson4/octree_poisson.hpp:749:41: error: no member named 'center' in 'OctNode<NodeData, Real>'
  749 |         temp=SquareDistance(children[i].center,p);
      |                             ~~~~~~~~~~~ ^
/pcl/surface/include/pcl/surface/3rdparty/poisson4/octree_poisson.hpp:810:38: error: no member named 'offset' in 'OctNode<NodeData, Real>'
  810 |       for(i=0;i<DIMENSION;i++){this->offset[i] = node.offset[i];}
      |                                ~~~~  ^
/pcl/surface/include/pcl/surface/3rdparty/poisson4/octree_poisson.hpp:820:51: error: reference to non-static member function must be called
  820 |       return ((const OctNode<NodeData,Real>*)v1)->depth-((const OctNode<NodeData,Real>*)v2)->depth;
      |              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~
/pcl/surface/include/pcl/surface/3rdparty/poisson4/octree_poisson.hpp:877:51: error: reference to non-static member function must be called
  877 |       return ((const OctNode<NodeData,Real>*)v2)->depth-((const OctNode<NodeData,Real>*)v1)->depth;
      |              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~
In file included from /pcl/surface/src/poisson.cpp:40:
In file included from /pcl/surface/include/pcl/surface/impl/poisson.hpp:49:
In file included from /pcl/surface/include/pcl/surface/3rdparty/poisson4/sparse_matrix.h:185:
/pcl/surface/include/pcl/surface/3rdparty/poisson4/sparse_matrix.hpp:231:20: error: no member named 'm_N' in 'SparseMatrix<T>'
  231 |       Resize(this->m_N, this->m_M);
      |              ~~~~  ^
/pcl/surface/include/pcl/surface/3rdparty/poisson4/sparse_matrix.hpp:231:31: error: no member named 'm_M' in 'SparseMatrix<T>'
  231 |       Resize(this->m_N, this->m_M);
      |                         ~~~~  ^
/pcl/surface/include/pcl/surface/3rdparty/poisson4/sparse_matrix.hpp:238:51: error: no member named 'Columns' in 'SparseMatrix<T>'
  238 |       for(int ij=0; ij < Min( this->Rows(), this->Columns() ); ij++)
      |                                             ~~~~  ^
/pcl/surface/include/pcl/surface/3rdparty/poisson4/sparse_matrix.hpp:238:37: error: no member named 'Rows' in 'SparseMatrix<T>'
  238 |       for(int ij=0; ij < Min( this->Rows(), this->Columns() ); ij++)
      |                               ~~~~  ^
/pcl/surface/include/pcl/surface/3rdparty/poisson4/sparse_matrix.hpp:391:25: error: no member named 'Columns' in 'SparseMatrix<T>'
  391 |       solution.Resize(M.Columns());
      |                       ~ ^
[ 23%] Linking CXX executable ../../bin/pcl_example_extract_indices
9 errors generated.
gmake[2]: *** [surface/CMakeFiles/pcl_surface.dir/build.make:328: surface/CMakeFiles/pcl_surface.dir/src/poisson.cpp.o] Error 1

In file included from /pcl/registration/src/correspondence_rejection_features.cpp:40:
/pcl/registration/include/pcl/registration/correspondence_rejection_features.h:274:25: error: no member named 'getClassName' in 'FeatureContainer<FeatureT>'
  274 |                   this->getClassName().c_str());
      |                   ~~~~  ^
/pcl/common/include/pcl/console/print.h:60:70: note: expanded from macro 'PCL_ERROR'
   60 | #define PCL_ERROR(...)   pcl::console::print (pcl::console::L_ERROR, __VA_ARGS__)
      |                                                                      ^~~~~~~~~~~
1 error generated.
gmake[2]: *** [registration/CMakeFiles/pcl_registration.dir/build.make:188: registration/CMakeFiles/pcl_registration.dir/src/correspondence_rejection_features.cpp.o] Error 1

[larshg]

Looks reasonable 😄