svnrdump: dump_editor: Fix issues related to per-revision pool
svnrdump: dump_editor: Fix issues related to per-revision pool

* subversion/svnrdump/dump_editor.c

  (open_root): Mention that `eb->pool` is a per-revision pool and
  clear it in every iteration. Make it a toplevel pool since the
  lifetime of `pool` is not known.

  (close_edit): Remove useless svn_pool_destroy cruft since logs show
  that this function is never actually called.

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