Description:
------------
stream_socket_client() can throw an unknown error when connection timeout is set to less than 1s due to a bug in php_openssl_subtract_timeval()

A PR has been raised https://github.com/php/php-src/pull/5422 

Test script:
---------------
https://gist.github.com/joec4i/ef1b1156ed79e23487400c68a5f693cb

// To test, run `php socket_test.php 10000 0.9 | grep error`

Expected result:
----------------
No connection errors

Tested X connections(timeout=0.1) with in xs with 0 errors

Actual result:
--------------
failed in 0.0037751197814941s, error.no=0, errstr=
failed in 0.0031719207763672s, error.no=0, errstr=
failed in 0.0026381015777588s, error.no=0, errstr=
failed in 0.0029230117797852s, error.no=0, errstr=
failed in 0.0027728080749512s, error.no=0, errstr=
Tested 2000 connections(timeout=0.9) with in 6.1318738460541s with 5 errors