COMP: fixed compilation error using llvm's libc++
COMP: fixed compilation error using llvm's libc++

ifstream's read() method returns a reference, which
can never be NULL yet vtkEnSightGoldBinaryReader was
comparing the result against NULL.  This fails to
compile if using llvm's libc++.  So, instead of
"if (read() == NULL)" it now does "if (!read())"
which does the right thing (I think)
since operator! is overloaded.

Change-Id: I5412da06795982826bb0df5c7dd82e53b1754e5d

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