Description:
------------
Currently, Built-in web server handle php://stdin as STDIN.

this behaviour may cause hang when reading raw POST data.
almost php web application uses file_get_contents("php://stdin") for reading raw data (like json).


Test script:
---------------
# client.php
<?php

$data = "Hello World";
$length = strlen($data);

file_get_contents("http://127.0.0.1:11111/", false, stream_context_create(array(
        "http" => array(
                "method" => "POST",
                "header" => "Content-type: application/octet-stream\r\nContent-Length: $length",
                "content" => $data,
        )
)));

# server.php (php -S 127.0.0.1:11111 server.php)
<?php
error_log(file_get_contents("php://stdin"));

Expected result:
----------------
# server.php
Hello World

Actual result:
--------------
// builtin web server waits console input.