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_da.utf-8.vim b/runtime/lang/menu_da.utf-8.vim
index a11213c..935a780 100644
--- a/runtime/lang/menu_da.utf-8.vim
+++ b/runtime/lang/menu_da.utf-8.vim
@@ -1,6 +1,7 @@
 " Menu Translations:	Danish
 " Maintainer:		scootergrisen
 " Last Change:		2020 Apr 23
+" Original translations
 
 " Quit when menu translations have already been done.
 if exists("did_menu_trans")