Support custom socket directory in pg_upgrade

When Who What
2018-12-01 20:45:49 Tom Lane (tgl) Closed in commitfest 2019-01 with status: Committed
2018-12-01 17:18:18 Tom Lane (tgl) Added tgl as committer
2018-12-01 13:26:11 Dmitry Dolgov (erthalion) Closed in commitfest 2018-11 with status: Moved to next CF
2018-10-25 14:05:54 Hironobu Suzuki (suzuki_hironobu) New status: Ready for Committer
2018-10-17 17:42:33 Hironobu Suzuki (suzuki_hironobu) Added suzuki_hironobu as reviewer
2018-10-10 07:54:30 Daniel Gustafsson (d_gustafsson) Changed authors to Daniel Gustafsson (d_gustafsson)
2018-10-10 07:54:16 Daniel Gustafsson (d_gustafsson) Attached mail thread E72DD5C3-2268-48A5-A907-ED4B34BEC223@yesql.se
2018-10-10 07:54:16 Daniel Gustafsson (d_gustafsson) Created patch record