GME: various robsutness fixes: memory leak, crashes, etc...

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@27178 f0d54148-0727-0410-94bb-9a71ac55c965
compilation fix

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@27179 f0d54148-0727-0410-94bb-9a71ac55c965