patch 9.1.0908: not possible to configure :messages

Problem:  not possible to configure :messages
Solution: add the 'messagesopt' option (Shougo Matsushita)

closes: #16068

Co-authored-by: h_east <h.east.727@gmail.com>
Signed-off-by: Shougo Matsushita <Shougo.Matsu@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/option.h b/src/option.h
index 18a7c2a..e747add 100644
--- a/src/option.h
+++ b/src/option.h
@@ -775,6 +775,7 @@
 #ifdef FEAT_MENU
 EXTERN long	p_mis;		// 'menuitems'
 #endif
+EXTERN char_u	*p_meo;		// 'messagesopt'
 #ifdef FEAT_SPELL
 EXTERN char_u	*p_msm;		// 'mkspellmem'
 #endif
@@ -794,7 +795,6 @@
 #endif
 EXTERN long	p_mouset;	// 'mousetime'
 EXTERN int	p_more;		// 'more'
-EXTERN long	p_mhi;		// 'msghistory'
 #ifdef FEAT_MZSCHEME
 EXTERN long	p_mzq;		// 'mzquantum
 # if defined(DYNAMIC_MZSCHEME)