Increase initdb's fallback value of max_connection to 20

When Who What
2018-03-08 16:31:11 Tom Lane (tgl) Closed in commitfest 2018-03 with status: Committed
2018-03-08 16:31:11 Tom Lane (tgl) Changed committer to tgl
2018-02-28 07:36:54 Michael Paquier (michael-kun) New status: Ready for Committer
2018-02-28 07:36:49 Michael Paquier (michael-kun) Changed reviewers to Michael Paquier (michael-kun)
2018-02-28 00:58:50 Kyotaro Horiguchi (horiguti) Changed authors to Kyotaro Horiguchi (horiguti)
2018-02-28 00:58:30 Kyotaro Horiguchi (horiguti) Attached mail thread 20180209.170823.42008365.horiguchi.kyotaro@lab.ntt.co.jp
2018-02-28 00:58:30 Kyotaro Horiguchi (horiguti) Created patch record