runtime(kconfig): add include to ftplugin (#14524)

related: #14521

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

Author: chrisbra

runtime/ftplugin/kconfig.vim

@@ -1,27 +1,22 @@
 " Vim filetype plugin file
 " Vim syntax file
-" Maintainer:           Christian Brabandt <cb@256bit.org>
-" Previous Maintainer:  Nikolai Weibull <now@bitwi.se>
-" Latest Revision:      2015-05-29
-" License:              Vim (see :h license)
+" Maintainer:		Christian Brabandt <cb@256bit.org>
+" Previous Maintainer:	Nikolai Weibull <now@bitwi.se>
+" Latest Revision:	2024-04-12
+" License:		Vim (see :h license)
 " Repository:		https://github.com/chrisbra/vim-kconfig
 
 if exists("b:did_ftplugin")
   finish
 endif
 let b:did_ftplugin = 1
 
-let s:cpo_save = &cpo
-set cpo&vim
-
-let b:undo_ftplugin = "setl com< cms< fo<"
+let b:undo_ftplugin = "setl inc< com< cms< fo<"
 
+setlocal include=source\\s\\+
 setlocal comments=:# commentstring=#\ %s formatoptions-=t formatoptions+=croql
 
 " For matchit.vim
 if exists("loaded_matchit")
   let b:match_words = '^\<menu\>:\<endmenu\>,^\<if\>:\<endif\>,^\<choice\>:\<endchoice\>'
 endif
-
-let &cpo = s:cpo_save
-unlet s:cpo_save