Clean up some elog messages and comments for do_pg_stop_backup and do_pg_start_backup

2019-01-01 00:04:41 Michael Paquier (michael-kun) Closed in commitfest 2019-01 with status: Committed 2019-01-01 00:04:41 Michael Paquier (michael-kun) Changed committer to michael-kun 2018-12-31 11:20:22 Peter Eisentraut (petere) New status: Ready for Committer 2018-12-29 15:31:26 Peter Eisentraut (petere) New status: Waiting on Author 2018-12-29 15:22:04 Peter Eisentraut (petere) Added petere as reviewer 2018-12-24 11:33:05 Michael Paquier (michael-kun) Changed authors to Michael Paquier (michael-kun) 2018-12-24 11:33:05 Michael Paquier (michael-kun) Changed reviewers to 2018-12-21 07:47:23 Michael Paquier (michael-kun) Changed reviewers to Michael Paquier (michael-kun) 2018-12-21 07:47:17 Michael Paquier (michael-kun) Attached mail thread 20181221040510.GA12599@paquier.xyz 2018-12-21 07:47:17 Michael Paquier (michael-kun) Created patch record