repmgrd: additional check for the upstream connection

It's possible the upstream server was intermittently unavailable in
the interval between checks, invalidating the upstream connection.
With check types "ping" and "connection", the connection would not be
restored, so if the availability check was successful, additionally
verify the upstream connection and restore if necessary.

Addresses GitHub #633.

repmgrd-physical.c

@@ -1443,6 +1443,7 @@ monitor_streaming_standby(void)
 	while (true)
 	{
 		log_verbose(LOG_DEBUG, "checking %s", upstream_node_info.conninfo);
+
 		if (check_upstream_connection(&upstream_conn, upstream_node_info.conninfo) == true)
 		{
 			set_upstream_last_seen(local_conn, upstream_node_info.node_id);
@@ -3088,8 +3089,6 @@ do_primary_failover(void)
 }
 
 
-
-
 static void
 update_monitoring_history(void)
 {