MXS-2005: Use log manager only after initialization

The log manager functions must not be used before it is initialized.

server/core/test/test_event.cc

@@ -574,10 +574,10 @@ int main()
 
     srandom(time(NULL));
 
-    mxs_log_set_syslog_enabled(true);
-
     if (mxs_log_init("TEST_EVENT", ".", MXS_LOG_TARGET_DEFAULT))
     {
+        mxs_log_set_syslog_enabled(true);
+
         errors += test_levels();
         errors += test_facilities();
         errors += test_events();