Ev2 shims: avoid a couple of segfaults by providing fetch kind/props/base functions for the client export editor.
Ev2 shims: avoid a couple of segfaults by providing fetch kind/props/base
functions for the client export editor.

* subversion/libsvn_client/export.c
  (fetch_kind_func, fetch_props_func, fetch_base_func): New.
  (svn_client_export5): Use the above as editor shim callbacks.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion