CPLSpawn() on Windows: quote arguments with spaces in them (#5469)

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@27328 f0d54148-0727-0410-94bb-9a71ac55c965
PDF: fix compilation problem with Podofo on Windows (patch by keosak, #5469)

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@27329 f0d54148-0727-0410-94bb-9a71ac55c965