Fix type conversion warnings in vtkPLY
Fix type conversion warnings in vtkPLY

This fixes a couple of type conversion warnings in
the vtkPLY class when compiling with GCC.

Change-Id: I25961ddb5d67bab0799a3378b081e52baae9f0d3

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