Update runtime files
diff --git a/runtime/indent/sdl.vim b/runtime/indent/sdl.vim
index 6ce30b6..40fe63f 100644
--- a/runtime/indent/sdl.vim
+++ b/runtime/indent/sdl.vim
@@ -1,7 +1,7 @@
" Vim indent file
" Language: SDL
" Maintainer: Michael Piefel <entwurf@piefel.de>
-" Last Change: 10 December 2011
+" Last Change: 2021 Oct 03
" Shamelessly stolen from the Vim-Script indent file
@@ -14,6 +14,8 @@
setlocal indentexpr=GetSDLIndent()
setlocal indentkeys+==~end,=~state,*<Return>
+let b:undo_indent = "setl inde< indk<"
+
" Only define the function once.
if exists("*GetSDLIndent")
" finish