SQLite: attempt to make VirtualOGR (and thus sqlite dialect) work even with a libsqlite3 compiled with SQLITE_OMIT_LOAD_EXTENSION (on Unix only)

git-svn-id: https://svn.osgeo.org/gdal/trunk@26245 f0d54148-0727-0410-94bb-9a71ac55c965
SQLite: don't reference unused symbol that only exists if SQLITE_HAS_COLUMN_METADATA

git-svn-id: https://svn.osgeo.org/gdal/trunk@26246 f0d54148-0727-0410-94bb-9a71ac55c965
Merge branch 'trunk' into trunk_mingw