runtime: set 'cpoptions' for line-continuation in various runtime files

closes: #17121

Signed-off-by: Eisuke Kawashima <e-kwsm@users.noreply.github.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/indent/cucumber.vim b/runtime/indent/cucumber.vim
index 5d144e4..33d4cc7 100644
--- a/runtime/indent/cucumber.vim
+++ b/runtime/indent/cucumber.vim
@@ -2,11 +2,14 @@
 " Language:	Cucumber
 " Maintainer:	Tim Pope <vimNOSPAM@tpope.org>
 " Last Change:	2023 Dec 28
+" 2025 Apr 16 by Vim Project (set 'cpoptions' for line continuation, #17121)
 
 if exists("b:did_indent")
   finish
 endif
 let b:did_indent = 1
+let s:cpo_save = &cpo
+set cpo&vim
 
 setlocal autoindent
 setlocal indentexpr=GetCucumberIndent()
@@ -95,4 +98,7 @@
   return prev.indent < 0 ? 0 : prev.indent
 endfunction
 
+let &cpo = s:cpo_save
+unlet s:cpo_save
+
 " vim:set sts=2 sw=2: