MDEV-4492 InnoDB generates non-existing link to manual based on the server version

mysql-test/suite/innodb/r/help_url.result

 create table innodb_table_monitor (a int) engine=InnoDB;
 Warnings:
-Warning	131	Using innodb_table_monitor is deprecated and it may be removed in future releases. Please use the InnoDB INFORMATION_SCHEMA tables instead, see http://dev.mysql.com/doc/refman/10.0/en/innodb-i_s-tables.html
+Warning	131	Using innodb_table_monitor is deprecated and it may be removed in future releases. Please use the InnoDB INFORMATION_SCHEMA tables instead, see http://dev.mysql.com/doc/refman/5.6/en/innodb-i_s-tables.html
 drop table innodb_table_monitor;

storage/innobase/include/univ.i

@@ -60,9 +60,7 @@ component, i.e. we show M.N.P as M.N */
 	IB_TO_STR(INNODB_VERSION_MINOR) "."	\
 	IB_TO_STR(INNODB_VERSION_BUGFIX)
 
-#define REFMAN "http://dev.mysql.com/doc/refman/"	\
-	IB_TO_STR(MYSQL_VERSION_MAJOR) "."		\
-	IB_TO_STR(MYSQL_VERSION_MINOR) "/en/"
+#define REFMAN "http://dev.mysql.com/doc/refman/5.6/en/"
 
 #ifdef MYSQL_DYNAMIC_PLUGIN
 /* In the dynamic plugin, redefine some externally visible symbols