Adjust logic so VTK_MAX_THREADS is always set.
Adjust logic so VTK_MAX_THREADS is always set.

gram526/VTK,msmolens/VTK,keithroe/vtkoptix,johnkit/vtk-dev,demarle/VTK,biddisco/VTK,johnkit/vtk-dev,daviddoria/PointGraphsPhase1,keithroe/vtkoptix,candy7393/VTK,johnkit/vtk-dev,daviddoria/PointGraphsPhase1,gram526/VTK,aashish24/VTK-old,gram526/VTK,daviddoria/PointGraphsPhase1,mspark93/VTK,mspark93/VTK,berendkleinhaneveld/VTK,SimVascular/VTK,collects/VTK,hendradarwin/VTK,gram526/VTK,msmolens/VTK,keithroe/vtkoptix,msmolens/VTK,msmolens/VTK,demarle/VTK,biddisco/VTK,jmerkow/VTK,sumedhasingla/VTK,demarle/VTK,biddisco/VTK,berendkleinhaneveld/VTK,hendradarwin/VTK,jmerkow/VTK,ashray/VTK-EVM,johnkit/vtk-dev,ashray/VTK-EVM,msmolens/VTK,berendkleinhaneveld/VTK,hendradarwin/VTK,mspark93/VTK,jmerkow/VTK,demarle/VTK,mspark93/VTK,candy7393/VTK,jmerkow/VTK,cjh1/VTK,SimVascular/VTK,cjh1/VTK,spthaolt/VTK,aashish24/VTK-old,keithroe/vtkoptix,aashish24/VTK-old,candy7393/VTK,sumedhasingla/VTK,mspark93/VTK,spthaolt/VTK,msmolens/VTK,collects/VTK,sankhesh/VTK,sumedhasingla/VTK,daviddoria/PointGraphsPhase1,demarle/VTK,sumedhasingla/VTK,msmolens/VTK,ashray/VTK-EVM,sankhesh/VTK,candy7393/VTK,sankhesh/VTK,aashish24/VTK-old,ashray/VTK-EVM,SimVascular/VTK,daviddoria/PointGraphsPhase1,SimVascular/VTK,SimVascular/VTK,msmolens/VTK,biddisco/VTK,SimVascular/VTK,biddisco/VTK,sumedhasingla/VTK,ashray/VTK-EVM,biddisco/VTK,keithroe/vtkoptix,gram526/VTK,sankhesh/VTK,spthaolt/VTK,aashish24/VTK-old,cjh1/VTK,berendkleinhaneveld/VTK,sankhesh/VTK,demarle/VTK,jmerkow/VTK,collects/VTK,hendradarwin/VTK,aashish24/VTK-old,cjh1/VTK,candy7393/VTK,hendradarwin/VTK,sumedhasingla/VTK,jmerkow/VTK,cjh1/VTK,SimVascular/VTK,demarle/VTK,keithroe/vtkoptix,collects/VTK,collects/VTK,collects/VTK,spthaolt/VTK,mspark93/VTK,sumedhasingla/VTK,berendkleinhaneveld/VTK,keithroe/vtkoptix,daviddoria/PointGraphsPhase1,candy7393/VTK,candy7393/VTK,SimVascular/VTK,demarle/VTK,mspark93/VTK,ashray/VTK-EVM,johnkit/vtk-dev,jmerkow/VTK,gram526/VTK,johnkit/vtk-dev,johnkit/vtk-dev,ashray/VTK-EVM,spthaolt/VTK,biddisco/VTK,spthaolt/VTK,sumedhasingla/VTK,ashray/VTK-EVM,jmerkow/VTK,gram526/VTK,berendkleinhaneveld/VTK,berendkleinhaneveld/VTK,keithroe/vtkoptix,gram526/VTK,sankhesh/VTK,sankhesh/VTK,cjh1/VTK,mspark93/VTK,hendradarwin/VTK,sankhesh/VTK,candy7393/VTK,spthaolt/VTK,hendradarwin/VTK