Fix build on Mac with PyQt.
Fix build on Mac with PyQt.

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