Postgresql GROUP BY query fix

Problem:

* warning: pg_query() [function.pg-query]: Query failed: ERROR: column "u.name" must appear in the GROUP BY clause or be used in an aggregate function in /websites/afilias.info/afilias.info-Build-#/current/includes/database.pgsql.inc on line 125.
* user warning: query: SELECT v.uid, v.hostname, v.timestamp, u.name FROM votingapi_vote v LEFT JOIN users u ON v.uid = u.uid WHERE v.content_type = 'advpoll' AND v.content_id = 30 GROUP BY v.uid, v.hostname, v.timestamp ORDER BY u.name ASC LIMIT 20 OFFSET 0 in /websites/afilias.info/afilias.info-Build-#/current/includes/database.pgsql.inc on line 144.

Patch attached: