Tentative fix for Windows build issue.
Tentative fix for Windows build issue.

1) error: '_snprintf_s' was not declared in this scope;

2) warning: operator[] for vtkStdString is ambiguos when used with
an integral literal index, because of the const char* conversion
operator.

Change-Id: I42b878078277b91509d8d24bbbcaf82aa08eb2a3

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