BUG: Fix black image from vtkImageReslice in slab mode.
BUG: Fix black image from vtkImageReslice in slab mode.

Platforms that used gcc-4.7 were producing black images on
TestImageResliceMapperSlab and other tests that used vtkImageReslice
in its "slab" mode.  I built gcc-4.7 on my own machine and was
able to reproduce the bug.  A pointer to an array was being used
after the end of the scope in which the array had been declared

Change-Id: I76340f8a5d029067b879e5d2c1c3d9229591e54e

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