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/ftplugin/go.vim b/runtime/ftplugin/go.vim
index 57fc73c..f3cae02 100644
--- a/runtime/ftplugin/go.vim
+++ b/runtime/ftplugin/go.vim
@@ -5,12 +5,16 @@
 " 2024 Jul 16 by Vim Project (add recommended indent style)
 " 2025 Mar 07 by Vim Project (add formatprg and keywordprg option #16804)
 " 2025 Mar 18 by Vim Project (use :term for 'keywordprg' #16911)
+" 2025 Apr 16 by Vim Project (set 'cpoptions' for line continuation, #17121)
 
 if exists('b:did_ftplugin')
   finish
 endif
 let b:did_ftplugin = 1
 
+let s:cpo_save = &cpo
+set cpo&vim
+
 setlocal formatoptions-=t
 setlocal formatprg=gofmt
 
@@ -45,4 +49,7 @@
   endfunc
 endif
 
+let &cpo = s:cpo_save
+unlet s:cpo_save
+
 " vim: sw=2 sts=2 et