remind message should display in dble.log when slow query was not written into slowlogs because of Authority or dir not exist

[yexiaoli88]

• dble version: 5.6.29-dble-9.9.9.9-60c3ca8-20180912064213

server.xml

 <system>
        <property name="defaultSqlParser">druidparser</property>
        <property name="charset">utf-8</property>
        <property name="processors">1</property>
        <property name="processorExecutor">5</property>
        <property name="enableSlowLog">1</property>
        <property name="slowLogBaseDir">./slowlogs</property>
        <property name="slowLogBaseName">slow-query</property>
        <property name="sqlSlowTime">1</property>
        <property name="flushSlowLogPeriod">10</property>
        <property name="flushSlowLogSize">5</property>
    </system>

• steps：
  step1. restart dble step 2 chmod 000 slowlogs or rm -rf slowlogs step3. execute slow query on dble client port
• expect result：
  1. slow query should not be written into slowlogs
     2 remind message should display in dble.log
• real result：
  1.slow query was not be written into slowlogs (same as expect) 2.dble.log has no remid message
• supplements：
  1.

/label ~BUG

[FlyingMao]

version：5.6.29-dble-9.9.9.9-06d1f9a203c576becf5f5bc2565b722cd981a5b3-20181224034323 step1 real result：.slow query was be written into slowlogs