Description:
------------
If diffirence between two dates less than second, `DateTime::diff` returns more than 1 year of difference.

`date_diff` contains same bug.

Works properly on: 
PHP 7.2.10-0ubuntu1 (cli) (built: Sep 13 2018 13:38:55) ( NTS )

Bugged on: 
PHP 7.2.12 (cli) (built: Nov  6 2018 16:40:25) ( NTS )

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

$utc = new DateTimeZone('utc');
$foo = new DateTime('2018-11-29 07:14:12.503985', $utc);
$bar = new DateTime('2018-11-29 07:14:12.000000', $utc);

print_r($foo->diff($bar));

Expected result:
----------------
DateInterval Object
(
    [y] => 0
    [m] => 0
    [d] => 0
    [h] => 0
    [i] => 0
    [s] => 0
    [f] => -0.503985
    [weekday] => 0
    [weekday_behavior] => 0
    [first_last_day_of] => 0
    [invert] => 0
    [days] => 0
    [special_type] => 0
    [special_amount] => 0
    [have_weekday_relative] => 0
    [have_special_relative] => 0
)

Actual result:
--------------
DateInterval Object
(
    [y] => -1
    [m] => 11
    [d] => 30
    [h] => 23
    [i] => 59
    [s] => 59
    [f] => 0.496015
    [weekday] => 0
    [weekday_behavior] => 0
    [first_last_day_of] => 0
    [invert] => 0
    [days] => 0
    [special_type] => 0
    [special_amount] => 0
    [have_weekday_relative] => 0
    [have_special_relative] => 0
)