drop proc_open skipif again

Might have been a red herring?

Author: nikic

ext/standard/tests/streams/proc_open_bug51800_right.phpt

@@ -1,11 +1,5 @@
 --TEST--
 Bug #51800 proc_open on Windows hangs forever, the right way to do it
---SKIPIF--
-<?php
-if (strpos(PHP_OS, 'FreeBSD') !== false) {
-    die("skip for FreeBSD");
-}
-?>
 --FILE--
 <?php
 $callee = __DIR__ . "/process_proc_open_bug51800_right.php";