KWSys Process: Add OpenBSD process tree kill support
KWSys Process: Add OpenBSD process tree kill support

Patch from Chuck Atkins <chuck.atkins@kitware.com>

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