Fix issue with vtkPExodusIIWriter when run on one processor
Fix issue with vtkPExodusIIWriter when run on one processor

vtkPExodusIIWriter segfaults when run on a single processor as
reported in http://www.paraview.org/Bug/view.php?id=13210.
The CheckBlockInfoMap() method should only be be execute when
the writer is running in a multiprocesor environment. Add guard
to check number of processors.

Change-Id: Iff92125e1160af4e8bf3c95e4942a226e44f3b45

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