runtime: Set b:undo_indent where missing (#12944)

Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/indent/hare.vim

@@ -2,6 +2,7 @@
 " Language: Hare
 " Maintainer: Amelia Clarke <me@rsaihe.dev>
 " Last Change: 2022 Sep 22
+"              2023 Aug 28 by Vim Project (undo_indent)
 
 if exists("b:did_indent")
   finish
@@ -40,6 +41,8 @@ setlocal cinwords=if,else,for,switch,match
 
 setlocal indentexpr=GetHareIndent()
 
+let b:undo_indent = "setl cin< cino< cinw< inde< indk<"
+
 function! FloorCindent(lnum)
   return cindent(a:lnum) / shiftwidth() * shiftwidth()
 endfunction