Added code to handle NULL whole extent in RequestUpdateExtent().
Added code to handle NULL whole extent in RequestUpdateExtent().

When structured data filters are used in a composite data pipeline,
it is possible that WHOLE_EXTENT() will not be available the
first time RequestUpdateExtent() is called. Filters that work with
the composite pipeline need to handle this. Fixed for
vtkSynchronizedTemplates3D. Will re-evaluate a broader fix in the
future.

Change-Id: I24051df9a132efa8409aa99cebf37e34b707f14d

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