[php-src] Issue #11901: DateTimeImmutable::createFromFormat() does not support documented 'X' year format argument

Issue: https://github.com/php/php-src/issues/11901 Author: ajgale ### Description According to the [docs](https://www.php.net/manual/en/datetimeimmutable.createfromformat), 'X' or 'x' are recognized in a format parameter string as > A full numeric representation of a year, up to 19 digits, optionally prefixed by + or - The following code: ```php <?php $result = \DateTimeImmutable::createFromFormat('X-m-d', '20000-01-01'); \var_dump($result); ``` Resulted in this output: ``` bool(false) ``` But I expected this output instead: ``` object(DateTimeImmutable)#1 (3) { ["date"]=> string(26) "20000-01-01 11:02:40.000000" ["timezone_type"]=> int(3) ["timezone"]=> string(14) "America/Denver" } ``` ### PHP Version PHP 8.1.2 ### Operating System _No response_