Make common_sql_weight employ standard SQL functions for the timestamp
difference in seconds.
Also replace UTC_TIMESTAMP in the MariaDB-specific part with CURRENT_TIMESTAMP
as it is the only occurence and GNU social sets UTC as a default timezone.
In a delete_orphan_files.php script simplify the main query considerably.
In clean_profiles.php stop using COUNT as if it is ANY, that is unnecessary
punishment for the database. Instead implement the anti-join with a
left outer join.
In Autocomplete and Activitypub_profile use joins instead of a WHERE OR
anti-pattern for the semi-joins.
In lib/ui/galleryaction.php replace a CROSS JOIN with an INNER JOIN.
In actions/sup.php remove a redundant subquery: WHERE is applied before
grouping either way.
