Remove unnecessary __.

* subversion/libsvn_repos/dump.c
  (tracker__trim): Rename to ...
  (tracker_trim): ... this.
  (tracker__add_entry): Rename to ...
  (tracker_add_entry): ... this.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1541579 13f79535-47bb-0310-9956-ffa450edef68