Fix a few warnings

git-svn-id: https://svn.osgeo.org/gdal/trunk@28057 f0d54148-0727-0410-94bb-9a71ac55c965
SWIG bindings: add Feature.GetFieldAsBinary()

git-svn-id: https://svn.osgeo.org/gdal/trunk@28058 f0d54148-0727-0410-94bb-9a71ac55c965