Fix runtime errors from -fsanitize=undefined

When Who What
2019-08-13 18:50:08 Peter Eisentraut (petere) Closed in commitfest 2019-09 with status: Rejected
2019-08-01 11:20:55 Thomas Munro (macdice) New status: Waiting on Author
2019-08-01 11:20:46 Thomas Munro (macdice) Closed in commitfest 2019-07 with status: Moved to next CF
2019-08-01 11:20:42 Thomas Munro (macdice) New status: Needs review
2019-06-29 16:18:24 didier gautheron (didier.users.sourceforge.net) New status: Waiting on Author
2019-06-29 16:18:12 didier gautheron (didier.users.sourceforge.net) Added didier.users.sourceforge.net as reviewer
2019-06-28 07:32:02 Fabien Coelho (calvin) Added calvin as reviewer
2019-06-11 08:42:29 Peter Eisentraut (petere) Changed authors to Peter Eisentraut (petere)
2019-06-11 08:42:12 Peter Eisentraut (petere) Attached mail thread e1a26ece-7057-a234-d87e-4ce1cdc9eaa0@2ndquadrant.com
2019-06-11 08:42:12 Peter Eisentraut (petere) Created patch record