vtkAMRFlashReaderInternal: don't return a pointer to temporary memory
vtkAMRFlashReaderInternal: don't return a pointer to temporary memory

The string only lives as long as its expression, so don't return its
internal c_str.

Change-Id: I32f9fc8ef9847baa645d5743d399b55782122114

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