The documentation specifically states that lwlock-release fires before
any released waiters have been awakened.  It worked that way until
ab5194e6, where is seems to have been
misplaced accidentally.  Move it back where it belongs.

Author: Craig Ringer <craig.ringer@enterprisedb.com>
Discussion: https://www.postgresql.org/message-id/CAGRY4nwxKUS_RvXFW-ugrZBYxPFFM5kjwKT5O+0+Stuga5b4+Q@mail.gmail.com