Fixing overflow issue that appeared with GCC compilers.
Fixing overflow issue that appeared with GCC compilers.

Thanks to Michael Stephens for the report and fix.

Change-Id: Ibe68819a81b011d3e3b0d8fefc2bc122834e8602

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