COMP: Fix buffer lookahead for wrapper-parser include directive.
COMP: Fix buffer lookahead for wrapper-parser include directive.

Commit 8977cc9c did not properly handle the 2-character lookahead
required for handling backslashes while preprocessing included files.
It would sometimes duplicate the character following the backslash.

Backport of fd79beff from master to release.

Change-Id: I554c2adf507989364b49b2732dea8388190f35f1

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