Fix reports under PHP7.2

You'll need to delete all reports made before applying this patch for it
to work right. However, all reports made after applying this patch will
appear correctly in `mod.php?/reports`.

This closes #300.

post.php

@@ -332,7 +332,7 @@ if (isset($_POST['delete'])) {
 		$query = prepare("INSERT INTO ``reports`` VALUES (NULL, :time, :ip, :board, :post, :reason)");
 		$query->bindValue(':time', time(), PDO::PARAM_INT);
 		$query->bindValue(':ip', $_SERVER['REMOTE_ADDR'], PDO::PARAM_STR);
-		$query->bindValue(':board', $board['uri'], PDO::PARAM_INT);
+		$query->bindValue(':board', $board['uri'], PDO::PARAM_STR);
 		$query->bindValue(':post', $id, PDO::PARAM_INT);
 		$query->bindValue(':reason', $reason, PDO::PARAM_STR);
 		$query->execute() or error(db_error($query));