BUG: Fix TestSetGet for vtkXOpenGLRenderWindow when DISPLAY is not set and VTK_USE_OFFSCREEN is ON. Also add output of DISPLAY env var when emitting vtkErrorMacro regarding bad X server connection.
BUG: Fix TestSetGet for vtkXOpenGLRenderWindow when DISPLAY is not set and VTK_USE_OFFSCREEN is ON. Also add output of DISPLAY env var when emitting vtkErrorMacro regarding bad X server connection.

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