databases/pgpool: Upgrade from 3.4.21 to 3.4.22

Changelog:

• Doc: Fix configuration change timing regarding memory_cache_enabled.
• Fix online recovery failed due to client_idle_limit_in_recovery in certain cases. (bug 431)
• Fix corner case bug when strip_quote() handle a empty query string. (bug 458)
• Fix Pgpool child segfault if failover occurs when trying to establish a connection.
• Fix Pgpool-II hang when idle_in_transaction_session_timeout = on.

MFH: 2019Q1