swig-py: Add typemap for the hunks field of svn_patch_t

* subversion/bindings/swig/include/svn_containers.swg
  (apr_array_header_t *hunks): New out typemap.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1548379 13f79535-47bb-0310-9956-ffa450edef68