Create one notification object for the lifetime of a load, rather than each time we need to perform a notification.
Create one notification object for the lifetime of a load, rather than each
time we need to perform a notification.

* subversion/libsvn_repos/load.c
  (parse_baton): Add notification struct.
  (parse_property_block, new_revision_record, maybe_add_with_history,
   new_node_record, close_node, close_revision): Use the established
    notification struct, rather than creating a new one.
  (svn_repos_get_fs_build_parser3): Intialize the notification struct.

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