MXS-1775 Introduce MonitorInstance::configure() function

The configuring of the monitor instance is now performed in a
separate function. That is in preparation for the moving of the
start function to maxscale::MonitorInstance.

server/modules/monitor/ndbclustermon/ndbclustermon.hh

@@ -39,5 +39,7 @@ private:
     NDBCMonitor(MXS_MONITOR* monitor);
     ~NDBCMonitor();
 
+    void configure(const MXS_CONFIG_PARAMETER* params);
+
     void main();
 };