patch 8.2.4420: menu translations are inconsistent

Problem:    Menu translations are inconsistent.
Solution:   Add a Makefile to convert between encodings. (Ada (Haowen) Yu,
            closes #9801)
diff --git a/runtime/lang/menu_de_de.latin1.vim b/runtime/lang/menu_de_de.latin1.vim
index d836118..17c748f 100644
--- a/runtime/lang/menu_de_de.latin1.vim
+++ b/runtime/lang/menu_de_de.latin1.vim
@@ -5,6 +5,7 @@
 "			        Johannes Zellner <johannes@zellner.org>
 " Last Change:	Mon, 1 April 2019
 " vim:set foldmethod=marker tabstop=8:
+" Original translations
 
 " Quit when menu translations have already been done.
 if exists("did_menu_trans")