Adding guard to incremental force layout SetFixed
Adding guard to incremental force layout SetFixed

Without this extra guard, this was causing invalid memory
accesses when the incremental layout had not yet been initialized.

Change-Id: Ic3d00c2d5ba2d93bafb5b3afcc333c21e5d58a2e

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