patch 8.1.2145: cannot map <C-H> when modifyOtherKeys is enabled

Problem:    Cannot map <C-H> when modifyOtherKeys is enabled.
Solution:   Add the <C-H> mapping twice, both with modifier and as 0x08.  Use
            only the first one when modifyOtherKeys has been detected.
diff --git a/src/menu.c b/src/menu.c
index 4096a05..e55cab6 100644
--- a/src/menu.c
+++ b/src/menu.c
@@ -372,7 +372,8 @@
 	else if (modes & MENU_TIP_MODE)
 	    map_buf = NULL;	/* Menu tips are plain text. */
 	else
-	    map_to = replace_termcodes(map_to, &map_buf, FALSE, TRUE, special);
+	    map_to = replace_termcodes(map_to, &map_buf,
+			REPTERM_DO_LT | (special ? REPTERM_SPECIAL : 0), NULL);
 	menuarg.modes = modes;
 #ifdef FEAT_TOOLBAR
 	menuarg.iconfile = icon;