Bug 15839: [QA Follow-up] Update existing rows in dbrev

Adding the default is fine for new records; we also should take care
of the pending existing ones.
Trivial addition to atomic update file.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Tested the dbrev again with existing unapproved reviews.

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>

installer/data/mysql/atomicupdate/bug_review.sql

@@ -1 +1,2 @@
 ALTER TABLE reviews CHANGE COLUMN approved approved tinyint(4) DEFAULT 0;
+UPDATE reviews SET approved=0 WHERE approved IS NULL;