libsmbconf: add "includes" to the forbidden_valnames[].

This removes the warning messages 'Unknown parameter encountered: "includes"'.

Michael
(This used to be commit b20019ceaa)

source3/lib/smbconf/smbconf_reg.c

@@ -52,6 +52,7 @@ static bool smbconf_reg_valname_forbidden(const char *valname)
 		"lock dir",
 		"config backend",
 		"include",
+		"includes", /* this has a special meaning internally */
 		NULL
 	};
 	const char **forbidden = NULL;