repmgrd: activate inactive node record at startup

If a PostgreSQL instance was shut down while repmgrd was running, and
repmgrd was subsequently restarted (this chain of events could occur
during e.g. a server reboot), the node record will have been set to
"inactive". Previously, in this case repmgrd would refuse to start up.
However, as we can determine the node is running, it should normally
be no problem to automatically set the node record to "active".

The old behaviour can be restored by setting the new parameter
"repmgrd_exit_on_inactive_node" to "true".

RM19604.

configfile.h

@@ -206,6 +206,7 @@ typedef struct
 	int			primary_notification_timeout;
 	int			repmgrd_standby_startup_timeout;
 	char		repmgrd_pid_file[MAXPGPATH];
+	bool		repmgrd_exit_on_inactive_node;
 	bool		standby_disconnect_on_failover;
 	int			sibling_nodes_disconnect_timeout;
 	ConnectionCheckType connection_check_type;