Description:
------------
Hi, 
Epoch time function strftime('%s') call returns empty on Windows but works on Linux.
Tested PHP builds:
PHP 7.3.2 (cli) (built: Feb  5 2019 23:14:21) ( NTS MSVC15 (Visual C++ 2017) x86)
PHP 7.3.4 (cli) (built: Apr  2 2019 22:13:15) ( NTS MSVC15 (Visual C++ 2017) x86)
PHP 7.0.33-0+deb9u3 (cli) (built: Mar  8 2019 10:01:24) ( NTS )

Cannot strftime('%s') be defined as alias to time()? If not can it be explicitly written in the manual (i.e. doesn't work in Windows).
Thanks. 

Test script:
---------------
<?php
echo "time()=".time()."\n";
echo "strftime('%s')=".strftime('%s')."\n";
?>

Expected result:
----------------
time()=1555236075
strftime('%s')=1555236075

Actual result:
--------------
time()=1555236100
strftime('%s')=