Fix mogstats for all non-postgres DB's :(

I doofused on the previous commit

mogstats

@@ -425,7 +425,7 @@ sub stats_for_devices {
 sub stats_for_files_sql {
     my $sql = 'SELECT dmid, classid, COUNT(classid), sum(length), sum(length::int8 * devcount::int8) FROM file GROUP BY 1, 2';
     return $sql if ($DB_TYPE eq 'Postgres');
-    $sql =~ s/::int4//g;
+    $sql =~ s/::int8//g;
     return $sql;
 }