Fix the example of ntp server address

* 去除alter外键约束时ob_ddl_timeout的约束，修改遗失返回码和dead code的问题

* 修改log记录的信息，修改移除dead code的代码

Enable pch and unity option in compiling process of rpm mode in order to keep consistent with other modes.

[Essence Securities]fix occur error after transform subquery pullup when view not set parent namespace stmt.