GME: fixes to avoid crash when insufficient permissions

git-svn-id: https://svn.osgeo.org/gdal/trunk@27189 f0d54148-0727-0410-94bb-9a71ac55c965
Fix memleak

git-svn-id: https://svn.osgeo.org/gdal/trunk@27190 f0d54148-0727-0410-94bb-9a71ac55c965