suppress warning if /dev/urandom is not readable (bug #997)

3rdparty/phpass/PasswordHash.php

@@ -48,7 +48,7 @@ class PasswordHash {
 	function get_random_bytes($count)
 	{
 		$output = '';
-		if (is_readable('/dev/urandom') &&
+		if (@is_readable('/dev/urandom') &&
 		    ($fh = @fopen('/dev/urandom', 'rb'))) {
 			$output = fread($fh, $count);
 			fclose($fh);