bug#27606: cp: copy directory attributes only

[Lion Yang]

   Hi,
   `--preserve=all` is very useful indeed. To directories, most of the
   time of copying attributes, we don't want to let `cp` mess up the files
   inside, I mean, I will do it manually. So there will be an
   `--attributes-only`.
   Go on. Target is a directory, we must treat it as a file. Otherwise it
   may think we are going to put the source INTO destination. So there
   will be a `--no-target-directory`.
   The issue is, copy_internal() does not work:
   (src/copy.c)
   1857   src_mode = src_sb.st_mode;
   1858
   1859   if (S_ISDIR (src_mode) && !x->recursive)
   1860     {
   1861       error (0, 0, ! x->install_mode /* cp */
   1862                    ? _("-r not specified; omitting directory %s")
   1863                    : _("omitting directory %s"),
   1864              quoteaf (src_name));
   1865       return false;
   1866     }
   This part says: if your source is a directory and you want to do
   something with it, you MUST do it recursively.
   This is not reasonable in such scenario. I propose to change or remove
   this limit to allow copying something of directory itself.
   Best regards
   Lion Yang