More merge.c private function doc improvements and local variable cleanup.
More merge.c private function doc improvements and local variable cleanup.

* subversion/libsvn_client/merge.c
  (do_directory_merge): Cleanup doc string.  Remove children_with_mergeinfo
  local variable, we already have it in NOTIFY_B argument.  Improve some of
  the internal comments to make it clearer what we are doing with the
  NOTIFY_B->children_with_mergeinfo->remaining_ranges as we drive the
  editor. 


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@872775 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion