Windows build of PDF: fix compilation issue with Visual Studio 2012 (#5744)

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@27988 f0d54148-0727-0410-94bb-9a71ac55c965
Fix previous commit (#5744)

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@27989 f0d54148-0727-0410-94bb-9a71ac55c965