standby switchover: improve directory check failure handling

It's possible that the remote data directory check will fail if e.g.
connection configuration is not consistent across all nodes. This
modification ensures a database error connection is reported, rather
than a spurios issue with the data directory configuration.

repmgr-client-global.h

@@ -221,6 +221,13 @@ typedef enum
 	JOIN_FAIL_NO_REPLICATION
 } standy_join_status;
 
+typedef enum
+{
+	REMOTE_ERROR_UNKNOWN = -1,
+	REMOTE_ERROR_NONE,
+	REMOTE_ERROR_DB_CONNECTION,
+	REMOTE_ERROR_CONNINFO_PARSE
+} t_remote_error_type;
 
 typedef struct ColHeader
 {