Fix PM count caching.

cache::get() returns null if the key wasn't found (at least when using
the Redis cache backend).

inc/mod/auth.php

@@ -125,7 +125,7 @@ if (isset($_COOKIE[$config['cookies']['mod']])) {
 function create_pm_header() {
 	global $mod, $config;
 	
-	if ($config['cache']['enabled'] && ($header = cache::get('pm_unread_' . $mod['id'])) !== false) {
+	if ($config['cache']['enabled'] && ($header = cache::get('pm_unread_' . $mod['id'])) != false) {
 		if ($header === true)
 			return false;
 	

inc/mod/pages.php

@@ -89,7 +89,7 @@ function mod_dashboard() {
 		}
 	}
 	
-	if (!$config['cache']['enabled'] || ($args['unread_pms'] = cache::get('pm_unreadcount_' . $mod['id'])) === false) {
+	if (!$config['cache']['enabled'] || ($args['unread_pms'] = cache::get('pm_unreadcount_' . $mod['id'])) == false) {
 		$query = prepare('SELECT COUNT(*) FROM `pms` WHERE `to` = :id AND `unread` = 1');
 		$query->bindValue(':id', $mod['id']);
 		$query->execute() or error(db_error($query));