Fix export visibility for vtkImageStencilIterator
Fix export visibility for vtkImageStencilIterator

As Imaging/Core has been split into mutliple modules classes
need access to iterator outside Imaging/Core

Change-Id: I0a096b87625060309d1390f29854bfe1ef1d1074

msmolens/VTK,biddisco/VTK,hendradarwin/VTK,ashray/VTK-EVM,cjh1/VTK,cjh1/VTK,mspark93/VTK,ashray/VTK-EVM,jmerkow/VTK,mspark93/VTK,sumedhasingla/VTK,gram526/VTK,SimVascular/VTK,jmerkow/VTK,collects/VTK,johnkit/vtk-dev,sankhesh/VTK,cjh1/VTK,biddisco/VTK,sankhesh/VTK,jmerkow/VTK,ashray/VTK-EVM,johnkit/vtk-dev,demarle/VTK,mspark93/VTK,aashish24/VTK-old,berendkleinhaneveld/VTK,berendkleinhaneveld/VTK,msmolens/VTK,berendkleinhaneveld/VTK,aashish24/VTK-old,aashish24/VTK-old,ashray/VTK-EVM,candy7393/VTK,msmolens/VTK,SimVascular/VTK,keithroe/vtkoptix,SimVascular/VTK,demarle/VTK,sankhesh/VTK,biddisco/VTK,collects/VTK,candy7393/VTK,collects/VTK,johnkit/vtk-dev,sankhesh/VTK,mspark93/VTK,sumedhasingla/VTK,jmerkow/VTK,berendkleinhaneveld/VTK,hendradarwin/VTK,ashray/VTK-EVM,demarle/VTK,candy7393/VTK,collects/VTK,mspark93/VTK,jmerkow/VTK,aashish24/VTK-old,msmolens/VTK,demarle/VTK,mspark93/VTK,biddisco/VTK,sankhesh/VTK,gram526/VTK,keithroe/vtkoptix,ashray/VTK-EVM,cjh1/VTK,sumedhasingla/VTK,SimVascular/VTK,jmerkow/VTK,candy7393/VTK,gram526/VTK,mspark93/VTK,sumedhasingla/VTK,candy7393/VTK,candy7393/VTK,candy7393/VTK,jmerkow/VTK,biddisco/VTK,johnkit/vtk-dev,johnkit/vtk-dev,aashish24/VTK-old,gram526/VTK,sankhesh/VTK,jmerkow/VTK,SimVascular/VTK,johnkit/vtk-dev,gram526/VTK,berendkleinhaneveld/VTK,gram526/VTK,cjh1/VTK,keithroe/vtkoptix,mspark93/VTK,keithroe/vtkoptix,hendradarwin/VTK,msmolens/VTK,johnkit/vtk-dev,gram526/VTK,ashray/VTK-EVM,SimVascular/VTK,berendkleinhaneveld/VTK,hendradarwin/VTK,SimVascular/VTK,hendradarwin/VTK,sumedhasingla/VTK,ashray/VTK-EVM,berendkleinhaneveld/VTK,demarle/VTK,cjh1/VTK,keithroe/vtkoptix,SimVascular/VTK,demarle/VTK,hendradarwin/VTK,demarle/VTK,biddisco/VTK,hendradarwin/VTK,biddisco/VTK,sumedhasingla/VTK,sankhesh/VTK,sankhesh/VTK,sumedhasingla/VTK,keithroe/vtkoptix,keithroe/vtkoptix,msmolens/VTK,candy7393/VTK,collects/VTK,sumedhasingla/VTK,keithroe/vtkoptix,demarle/VTK,collects/VTK,msmolens/VTK,msmolens/VTK,gram526/VTK,aashish24/VTK-old