Description:
------------
Creation of new xmlwriter using memory fails. Script stops at same line. In Apache error log notice is writen:
[notice] child pid 363 exit signal Bus error (10)

Reproduce code:
---------------
$data = array(
    "foo" => 456,
    "bar" => 789,
    "aaa" => array(
        "abc" => 111
    )
);

$xml = new XmlWriter();
$xml->openMemory(); // script stopes in this line
$xml->startDocument('1.0', 'UTF-8');
$xml->startElement('root');

function write(XMLWriter $xml, $data){
    foreach($data as $key => $value){
        if(is_array($value)){
            $xml->startElement($key);
            write($xml, $value);
            $xml->endElement();
            continue;
        }
        $xml->writeElement($key, $value);
    }
}
write($xml, $data);

$xml->endElement();
echo $xml->outputMemory(true);

Expected result:
----------------
<?xml version="1.0" encoding="UTF-8"?>
<root><foo>456</foo><bar>789</bar><aaa><abc>111</abc></aaa></root>

Actual result:
--------------
Blank Screen