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_fr_fr.latin1.vim b/runtime/lang/menu_fr_fr.latin1.vim
index bd045d7..ef741d7 100644
--- a/runtime/lang/menu_fr_fr.latin1.vim
+++ b/runtime/lang/menu_fr_fr.latin1.vim
@@ -4,6 +4,7 @@
 " Contributors:		David Blanchet <david.blanchet@free.fr>
 " 			Gabriel Dupras <gabrieldupras@gmail.com>
 " Last Change:		2021 Feb 16
+" Original translations
 
 " Quit when menu translations have already been done.
 if exists("did_menu_trans")