SQL in 4.3.alpha1.mysql.tpl can fail if civicrm_dashboard_contact references deleted contacts

Unsure how this DB got into a state where there are civicrm_dashboard_contact.contact_id values which aren't in civicrm_contact.id, but that's where it is.

Anyway, we can handle that pretty easily (either a JOIN or, better IMO, cleaning them out).