COMP: Fix for conversion to non-pointer like type warning
COMP: Fix for conversion to non-pointer like type warning

Fixes the following warning (Wrapping):

ITK/Modules/Core/Common/include/itkCellInterface.h:368:61: warning: converting to non-pointer type 'itk::CellInterface<double, itk::CellTraitsInfo<2, double, double, long unsigned int, long unsigned int, long unsigned int, itk::Point<double, 2u>, itk::MapContainer<long unsigned int, itk::Point<double, 2u> >, std::set<long unsigned int> > >::CoordRepType {aka double}' from NULL [-Wconversion-null]
CoordRepType GetBoundingBoxDiagonalLength2(void) { return NULL; }

Change-Id: I88c79d7ebf73e38a611f773cd9242684fbbdec72

richardbeare/ITK,atsnyder/ITK,fedral/ITK,malaterre/ITK,spinicist/ITK,BRAINSia/ITK,PlutoniumHeart/ITK,LucasGandel/ITK,jcfr/ITK,fedral/ITK,fedral/ITK,ajjl/ITK,Kitware/ITK,thewtex/ITK,LucHermitte/ITK,vfonov/ITK,PlutoniumHeart/ITK,richardbeare/ITK,thewtex/ITK,richardbeare/ITK,jmerkow/ITK,jcfr/ITK,hjmjohnson/ITK,fbudin69500/ITK,jmerkow/ITK,biotrump/ITK,fedral/ITK,stnava/ITK,LucasGandel/ITK,BlueBrain/ITK,BlueBrain/ITK,stnava/ITK,PlutoniumHeart/ITK,heimdali/ITK,malaterre/ITK,richardbeare/ITK,jcfr/ITK,LucasGandel/ITK,InsightSoftwareConsortium/ITK,InsightSoftwareConsortium/ITK,malaterre/ITK,PlutoniumHeart/ITK,jmerkow/ITK,biotrump/ITK,hendradarwin/ITK,BlueBrain/ITK,hjmjohnson/ITK,vfonov/ITK,atsnyder/ITK,biotrump/ITK,atsnyder/ITK,richardbeare/ITK,hjmjohnson/ITK,msmolens/ITK,LucasGandel/ITK,stnava/ITK,spinicist/ITK,atsnyder/ITK,jcfr/ITK,biotrump/ITK,hendradarwin/ITK,msmolens/ITK,zachary-williamson/ITK,BlueBrain/ITK,fbudin69500/ITK,atsnyder/ITK,ajjl/ITK,fedral/ITK,heimdali/ITK,blowekamp/ITK,PlutoniumHeart/ITK,zachary-williamson/ITK,thewtex/ITK,richardbeare/ITK,jmerkow/ITK,thewtex/ITK,Kitware/ITK,msmolens/ITK,blowekamp/ITK,biotrump/ITK,spinicist/ITK,fbudin69500/ITK,BRAINSia/ITK,LucasGandel/ITK,stnava/ITK,atsnyder/ITK,BlueBrain/ITK,hendradarwin/ITK,stnava/ITK,fedral/ITK,stnava/ITK,PlutoniumHeart/ITK,BRAINSia/ITK,ajjl/ITK,ajjl/ITK,InsightSoftwareConsortium/ITK,msmolens/ITK,vfonov/ITK,zachary-williamson/ITK,fedral/ITK,fbudin69500/ITK,PlutoniumHeart/ITK,jcfr/ITK,LucHermitte/ITK,malaterre/ITK,jmerkow/ITK,LucHermitte/ITK,LucHermitte/ITK,heimdali/ITK,thewtex/ITK,malaterre/ITK,stnava/ITK,InsightSoftwareConsortium/ITK,hendradarwin/ITK,richardbeare/ITK,jmerkow/ITK,spinicist/ITK,BRAINSia/ITK,blowekamp/ITK,atsnyder/ITK,spinicist/ITK,thewtex/ITK,Kitware/ITK,LucHermitte/ITK,hendradarwin/ITK,InsightSoftwareConsortium/ITK,InsightSoftwareConsortium/ITK,stnava/ITK,hjmjohnson/ITK,malaterre/ITK,atsnyder/ITK,ajjl/ITK,ajjl/ITK,BRAINSia/ITK,vfonov/ITK,heimdali/ITK,hendradarwin/ITK,msmolens/ITK,fbudin69500/ITK,stnava/ITK,InsightSoftwareConsortium/ITK,thewtex/ITK,fbudin69500/ITK,spinicist/ITK,zachary-williamson/ITK,blowekamp/ITK,msmolens/ITK,vfonov/ITK,LucHermitte/ITK,BlueBrain/ITK,blowekamp/ITK,heimdali/ITK,LucasGandel/ITK,ajjl/ITK,BlueBrain/ITK,malaterre/ITK,vfonov/ITK,spinicist/ITK,vfonov/ITK,malaterre/ITK,heimdali/ITK,biotrump/ITK,msmolens/ITK,ajjl/ITK,hjmjohnson/ITK,zachary-williamson/ITK,zachary-williamson/ITK,hjmjohnson/ITK,biotrump/ITK,PlutoniumHeart/ITK,BlueBrain/ITK,zachary-williamson/ITK,heimdali/ITK,blowekamp/ITK,fedral/ITK,zachary-williamson/ITK,jcfr/ITK,jmerkow/ITK,heimdali/ITK,blowekamp/ITK,LucHermitte/ITK,spinicist/ITK,spinicist/ITK,Kitware/ITK,BRAINSia/ITK,LucasGandel/ITK,jmerkow/ITK,Kitware/ITK,vfonov/ITK,msmolens/ITK,LucasGandel/ITK,malaterre/ITK,jcfr/ITK,hendradarwin/ITK,atsnyder/ITK,jcfr/ITK,biotrump/ITK,Kitware/ITK,Kitware/ITK,vfonov/ITK,fbudin69500/ITK,hjmjohnson/ITK,BRAINSia/ITK,blowekamp/ITK,hendradarwin/ITK,LucHermitte/ITK,fbudin69500/ITK,zachary-williamson/ITK