Fix issue #4044, "empty parents of externals not removed along with externals on update".
Fix issue #4044, "empty parents of externals not removed along with externals
on update".

* subversion/libsvn_client/externals.c
  (svn_client__handle_externals): When removing externals, remove the
    defining directory if it ends up being unversioned and empty.
    This is a workaround for our inability to remove the defining
    dir when delete_entry() in the update editor is called for it.
    At that point, external children have not been removed yet, so
    the update editor leaves the directory behind on disk, unversioned,
    because it isn't empty.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1188774 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion