Removed unused CONSTANT_DECL macro
Removed unused CONSTANT_DECL macro

It appears nowhere else in the codebase.
Found this dead code using -Wunused-macros.

There's an off chance, I suppose, that it
is expected by a system header, but I
don't think so.

Change-Id: Ib306770cd9c2aab05866f2bbdabb6f1aba2d435c

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