Use strict array_search in DatabasePostgres.php

array_search( 'FOR UPDATE', array( 'OFFSET' => 0 ) ) gives 'OFFSET'
array_search( 'FOR UPDATE', array( 'OFFSET' => 0 ), true ) gives false

This avoids FOR UPDATE on QueryPage query like Special:BrokenRedirect.

Bug: 62104
Change-Id: Iaa6db6b3ce5eaf940e7a8afe459955f19ad0e01f
Merge "Use strict array_search in DatabasePostgres.php"