Provide facility to ignore all marked files in vc

* lisp/vc/vc-dir.el: (vc-dir-ignore) With prefix argument, ignore all
marked files (bug#37240).

etc/NEWS

@@ -743,6 +743,10 @@ file.
 *** New customizable variable 'vc-find-revision-no-save'.
 With non-nil, 'vc-find-revision' doesn't write the created buffer to file.
 
+---
+*** 'vc-dir-ignore' now takes a prefix argument to ignore all marked
+files.
+
 *** New customizable variable 'vc-git-grep-template'.
 This new variable allows customizing the default arguments passed to
 'git-grep' when 'vc-git-grep' is used.

lisp/vc/vc-dir.el

@@ -864,10 +864,18 @@ with the command \\[tags-loop-continue]."
    delimited)
   (fileloop-continue))
 
-(defun vc-dir-ignore ()
-  "Ignore the current file."
-  (interactive)
-  (vc-ignore (vc-dir-current-file)))
+(defun vc-dir-ignore (&optional arg)
+  "Ignore the current file.
+If a prefix argument is given, ignore all marked files."
+  (interactive "P")
+  (if arg
+      (ewoc-map
+       (lambda (filearg)
+	 (when (vc-dir-fileinfo->marked filearg)
+	   (vc-ignore (vc-dir-fileinfo->name filearg))
+	   t))
+       vc-ewoc)
+    (vc-ignore (vc-dir-current-file))))
 
 (defun vc-dir-current-file ()
   (let ((node (ewoc-locate vc-ewoc)))