Ignore .dir-locals-2.el files more

* lisp/emacs-lisp/shadow.el (load-path-shadows-find):
* lisp/emacs-lisp/bytecomp.el (byte-recompile-directory): Ignore
.dir-locals-2.el, too (bug#23257).

lisp/emacs-lisp/bytecomp.el

@@ -1857,8 +1857,7 @@ also be compiled."
                         (file-readable-p source)
 			(not (string-match "\\`\\.#" file))
                         (not (auto-save-file-name-p source))
-                        (not (string-equal dir-locals-file
-                                           (file-name-nondirectory source))))
+                        (not (member source (dir-locals--all-files directory))))
                    (progn (cl-incf
                            (pcase (byte-recompile-file source force arg)
                              ('no-byte-compile skip-count)

lisp/emacs-lisp/shadow.el

@@ -115,9 +115,12 @@ See the documentation for `list-load-path-shadows' for further information."
 	  ;; FILE now contains the current file name, with no suffix.
 	  (unless (or (member file files-seen-this-dir)
 		      ;; Ignore these files.
-		      (member file (list "subdirs" "leim-list"
-					 (file-name-sans-extension
-					  dir-locals-file))))
+		      (member file
+                              (list "subdirs" "leim-list"
+				    (file-name-sans-extension dir-locals-file)
+                                    (concat
+				     (file-name-sans-extension dir-locals-file)
+                                     "-2"))))
 	    ;; File has not been seen yet in this directory.
 	    ;; This test prevents us declaring that XXX.el shadows
 	    ;; XXX.elc (or vice-versa) when they are in the same directory.