Description:
------------
When attempting to create a closure from an FFI function, it results in a segfault  when trying to call the closure.

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

$header = '
int printf(const char*, ...);

';

$ffi = FFI::cdef($header, 'libc.so.6');

$cb = Closure::fromCallable([$ffi, 'printf']);

$cb("Hello World\n");

Expected result:
----------------
Hello World

Actual result:
--------------
Program received signal SIGSEGV, Segmentation fault.
0x0000555555ae0c0d in zend_closure_call_magic (execute_data=0x7ffff3a13180, return_value=0x7ffff3a13100) at /.../Zend/zend_closures.c:249
249                     EX(func)->internal_function.scope->__callstatic : EX(func)->internal_function.scope->__call;