LIBKML: avoid writing empty <Style> in some circumstances (ATC 65)

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@26950 f0d54148-0727-0410-94bb-9a71ac55c965
SQLite dialect: avoid warning when setting a NULL spatial filter on a layer without geometry

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@26951 f0d54148-0727-0410-94bb-9a71ac55c965