vtkExecutionTimer: Add missing comment to satisfy HeaderTest
vtkExecutionTimer: Add missing comment to satisfy HeaderTest

Fix the vtkFiltersCore-HeaderTest by labeling the private copy
constructor and assignment operator with the required "Not implemented"
comment.

Change-Id: Ic873fd1d1dfa3a6827d9da0d29e96f14bd93b343

gram526/VTK,hendradarwin/VTK,collects/VTK,gram526/VTK,hendradarwin/VTK,gram526/VTK,gram526/VTK,ashray/VTK-EVM,johnkit/vtk-dev,ashray/VTK-EVM,candy7393/VTK,msmolens/VTK,berendkleinhaneveld/VTK,msmolens/VTK,mspark93/VTK,jmerkow/VTK,collects/VTK,keithroe/vtkoptix,johnkit/vtk-dev,sumedhasingla/VTK,biddisco/VTK,sankhesh/VTK,biddisco/VTK,sankhesh/VTK,biddisco/VTK,sumedhasingla/VTK,mspark93/VTK,hendradarwin/VTK,sankhesh/VTK,sankhesh/VTK,candy7393/VTK,candy7393/VTK,candy7393/VTK,mspark93/VTK,aashish24/VTK-old,keithroe/vtkoptix,biddisco/VTK,mspark93/VTK,SimVascular/VTK,keithroe/vtkoptix,keithroe/vtkoptix,sankhesh/VTK,johnkit/vtk-dev,jmerkow/VTK,candy7393/VTK,biddisco/VTK,demarle/VTK,SimVascular/VTK,jmerkow/VTK,hendradarwin/VTK,collects/VTK,keithroe/vtkoptix,msmolens/VTK,ashray/VTK-EVM,ashray/VTK-EVM,berendkleinhaneveld/VTK,mspark93/VTK,berendkleinhaneveld/VTK,demarle/VTK,ashray/VTK-EVM,gram526/VTK,demarle/VTK,msmolens/VTK,keithroe/vtkoptix,keithroe/vtkoptix,collects/VTK,jmerkow/VTK,sankhesh/VTK,sankhesh/VTK,SimVascular/VTK,jmerkow/VTK,SimVascular/VTK,gram526/VTK,gram526/VTK,sumedhasingla/VTK,SimVascular/VTK,keithroe/vtkoptix,aashish24/VTK-old,johnkit/vtk-dev,hendradarwin/VTK,SimVascular/VTK,hendradarwin/VTK,demarle/VTK,sumedhasingla/VTK,sumedhasingla/VTK,berendkleinhaneveld/VTK,SimVascular/VTK,berendkleinhaneveld/VTK,msmolens/VTK,jmerkow/VTK,aashish24/VTK-old,candy7393/VTK,ashray/VTK-EVM,demarle/VTK,gram526/VTK,sankhesh/VTK,johnkit/vtk-dev,msmolens/VTK,sumedhasingla/VTK,hendradarwin/VTK,collects/VTK,ashray/VTK-EVM,sumedhasingla/VTK,SimVascular/VTK,jmerkow/VTK,johnkit/vtk-dev,berendkleinhaneveld/VTK,aashish24/VTK-old,biddisco/VTK,biddisco/VTK,berendkleinhaneveld/VTK,demarle/VTK,demarle/VTK,mspark93/VTK,msmolens/VTK,mspark93/VTK,jmerkow/VTK,johnkit/vtk-dev,ashray/VTK-EVM,msmolens/VTK,sumedhasingla/VTK,aashish24/VTK-old,aashish24/VTK-old,demarle/VTK,candy7393/VTK,mspark93/VTK,candy7393/VTK,collects/VTK