Description:
------------
When declaring a function which returns a pointer, any calling
convention specifier is not recognized at the proper position (at
least the proper position for MSVC; not sure about other
compilers).

It appears to be possible to work around that issue by placing the
calling convention specifier between the base type and the `*` (or
even by placing it between `extern` and the base type), but we
should support the proper order as well.

This issue has been found by Alexander Lisachenko.


Test script:
---------------
<?php
$ffi = FFI::cdef(
    'char * __cdecl get_zend_version(void);',
    'php7_debug.dll'
);
echo FFI::string($ffi->get_zend_version());


Expected result:
----------------
Zend Engine v3.4.0-dev, Copyright (c) Zend Technologies

Actual result:
--------------
Fatal error: Uncaught FFI\ParserException: unexpected '__cdecl' at line 1 in %s:4