GPKG: initialize variable

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@26867 f0d54148-0727-0410-94bb-9a71ac55c965
ogr_formats.html: move GeoPackage line

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@26868 f0d54148-0727-0410-94bb-9a71ac55c965