Add support for Pgpool-II 4.2.

Add support for Pgpool-II 4.2.
Patch is created by Kawamoto Masaya.

Added parameters are:
    - backend_clustering_mode
    - ssl_crl_file
    - ssl_passphrase_command
    - log_disconnections
    - logging_collector
    - log_directory
    - log_filename
    - log_file_mode
    - log_truncate_on_rotation
    - log_rotation_age
    - log_rotation_size
    - read_only_function_list
    - write_function_list
    - primary_routing_query_pattern_list
    - dml_adaptive_object_relationship_list
    - hostname
    - pgpool_port
    - heartbeat_hostname
    - heartbeat_port
    - cache_safe_memqcache_table_list
    - cache_unsafe_memqcache_table_list

Deleted parameters are:
    - replication_mode
    - master_slave_mode
    - master_slave_sub_mode
    - white_function_list
    - black_function_list
    - black_query_pattern_list
    - wd_hostname
    - wd_port
    - wd_heartbeat_port
    - heartbeat_destination
    - heartbeat_destination_port
    - white_memqcache_table_list
    - black_memqcache_table_list
    - other_pgpool_hostname
    - other_pgpool_port
    - other_wd_port