MXS-2057 Add log output for system test, and two random code fixes

maxscale-system-test/testconnections.cpp

@@ -1255,6 +1255,7 @@ static int read_log(const char* name, char** err_log_content_p)
             err_log_content[size] = '\0';
             // printf("s=%ld\n", strlen(err_log_content));
             * err_log_content_p = err_log_content;
+            fclose(f);
             return 0;
         }
         else

maxutils/maxbase/include/maxbase/stopwatch.hh

@@ -49,7 +49,7 @@ struct Duration : public Clock::duration
     }
 
     /** To seconds */
-    double secs()
+    double secs() const
     {
         return std::chrono::duration<double>(*this).count();
     }

server/core/routingworker.cc

@@ -1020,6 +1020,7 @@ void RoutingWorker::check_systemd_watchdog()
             {
                 s_watchdog_next_check = now + s_watchdog_interval;
 #ifdef HAVE_SYSTEMD
+                MXS_DEBUG("systemd watchdog keep-alive ping: sd_notify(false, \"WATCHDOG=1\")");
                 sd_notify(false, "WATCHDOG=1");
 #endif
                 std::for_each(this_unit.ppWorkers, this_unit.ppWorkers + this_unit.nWorkers,