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_is_is.latin1.vim b/runtime/lang/menu_is_is.latin1.vim
index 9616c6c..bcb7096 100644
--- a/runtime/lang/menu_is_is.latin1.vim
+++ b/runtime/lang/menu_is_is.latin1.vim
@@ -2,6 +2,7 @@
 " Maintainer:		Jón Arnar Briem <jonbriem@gmail.com>
 " Originally By:	Jón Arnar Briem <jonbriem@gmail.com>
 " Last Change:	Sun, 24 Mar 2019 22:40:00 CEST
+" Original translations
 " vim:set foldmethod=marker tabstop=8:
 
 " Quit when menu translations have already been done.