Log Message:
pgpool2: update to 4.2.2.

Based on a diff provided by Mustafa Dogan.

4.2.1 and 4.2.2 are bugfix releases.

4.2 contains new features and enhancements, including:

    Some items in the configuration file pgpool.conf are vastly
    enhanced for easier configuration and administration.

    Implement logging_collector for easier log management.

    Implement log_disconnections to collect disconnection logs.

    Implement pg_enc and pg_md5 to allow to register multiple
    passwords at once.

    Allow to show statistics of health check by using SHOW
    POOL_HEALTH_CHECK_STATS command, and also allow to show statistics
    of issued SQL by using SHOW POOL_BACKEND_STATS command.

    New PCP command pcp_reload_config is added.

    Now it is possible to omit write_function_list and
    read_only_function_list by looking at system catalog information.

    Add new clustering mode snapshot_isolation_mode which guarantees
    not only data modifications to multiple PostgreSQL but read
    consistency.

    Support LDAP authentication between clients and Pgpool-II.

    Add ssl_crl_file and ssl_passphrase_command to SSL configuration.

    Import PostgreSQL 13's SQL parser.