Python bindings: make ogr.CreateGeometryFromWkt() and SpatialReference.ImportFromWkt() propery validate their argument (#5302)

git-svn-id: https://svn.osgeo.org/gdal/trunk@26644 f0d54148-0727-0410-94bb-9a71ac55c965
Merge branch 'trunk' into trunk_travis_macosx