Description:
------------
DateTime formats can be created using format() which have >4 digits in the year, which cannot be parsed using createFromFormat() with the same format-string. As seen below the same format is used both times.

This bug report looks absurd, but I've had similar issues been auto-reported to my crash archive when users put absurd values in configuration, and this appears to be why.

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

$datetime = new \DateTime('@' . PHP_INT_MAX);

$str = $datetime->format("Y-m-d H:i:s O");
var_dump($str); //275808-11-04 10:06:43 +0000

var_dump(\DateTime::createFromFormat("Y-m-d H:i:s O", $str)); //bool(false)

?>

Expected result:
----------------
Either:

bool(false)
bool(false)

OR

string(33) "292277026596-12-04 15:30:07 +0000
object(DateTime)#2 (3) {
  ["date"]=>
  string(34) "292277026596-12-04 15:30:07.000000
  ["timezone_type"]=>
  int(1)
  ["timezone"]=>
  string(6) "+00:00"
}

Actual result:
--------------
string(33) "292277026596-12-04 15:30:07 +0000"
bool(false)