Log Message:
Changes 8.4.1:
* Fix WAL page header initialization at the end of archive recovery
* Fix "cannot make new WAL entries during recovery" error
* Fix problem that could make expired rows visible after a crash
* Disallow "RESET ROLE" and "RESET SESSION AUTHORIZATION" inside
  security-definer functions
* Make "LOAD" of an already-loaded loadable module into a no-op
* Make window function PARTITION BY and ORDER BY items always be
  interpreted as simple expressions
* Fix several errors in planning of semi-joins
* Fix handling of whole-row references to subqueries that are within
  an outer join
* Fix Windows shared-memory allocation code
* Fix locale handling with plperl
* Fix handling of reloptions to ensure setting one option doesn't
  force default values for others
* Ensure that a "fast shutdown" request will forcibly terminate open
  sessions, even if a "smart shutdown" was already in progress
* Avoid memory leak for array_agg() in GROUP BY queries
* Treat to_char(..., 'TH') as an uppercase ordinal suffix with 'HH'/'HH12'