Description:
------------
When instantiating ReflectionFunction on the session_start() function and calling the getParameters() method, the optional parameter "options" is not returned.

All PHP versions affected.

Test script:
---------------
<?php

$reflection = new ReflectionFunction('session_start');
var_dump($reflection->getParameters());

?>

Expected result:
----------------
array(1) {
  [0]=>
  object(ReflectionParameter)#2 (1) {
    ["name"]=>
    string(2) "name"
  }
}

Actual result:
--------------
array(0) {
}