Problem - The default port number shown in SHOW SLAVE HOSTS is always 3306 
          though the slave is actually listening on a different port number.
          This is a problem as the user can not be sure whether this port 
          value can be trusted and so client trying to read replication 
          topology can get confused.

Fix - 3306 ceases to be the default value of report-port. Moreover report-port
      does not have a static default any longer.
      Instead we initialize report-port to 0 as the new default value and change
      it based on two checks :

      1) If report_port is not set, the slave reports the port number its listening 
         on. (i.e. if report-port is not set we get the actual value of the slave's 
         port number).

      2) If report-port is set, we show the value report-port is set to, as the slave's
         port number.