ENH: Added signed char instantiation.

Author: bradking

Filtering/vtkImageIterator.cxx

@@ -17,6 +17,7 @@
 
 #ifndef VTK_NO_EXPLICIT_TEMPLATE_INSTANTIATION
 
+template class VTK_FILTERING_EXPORT vtkImageIterator<signed char>;
 template class VTK_FILTERING_EXPORT vtkImageIterator<char>;
 template class VTK_FILTERING_EXPORT vtkImageIterator<int>;
 template class VTK_FILTERING_EXPORT vtkImageIterator<long>;

Filtering/vtkImageProgressIterator.cxx

@@ -24,6 +24,7 @@
 
 #ifndef VTK_NO_EXPLICIT_TEMPLATE_INSTANTIATION
 
+template class VTK_FILTERING_EXPORT vtkImageProgressIterator<signed char>;
 template class VTK_FILTERING_EXPORT vtkImageProgressIterator<char>;
 template class VTK_FILTERING_EXPORT vtkImageProgressIterator<int>;
 template class VTK_FILTERING_EXPORT vtkImageProgressIterator<long>;