As of commit 81b2f3e[1], `parse_url()` accepts URLs with a zero port,
but does not report that port, what is wrong in hindsight.
Since the port number is stored as `unsigned short` there is no way to
distinguish between port zero and no port. For BC reasons, we thus
introduce `parse_url_ex2()` which accepts an output parameter that
allows that distinction, and use the new function to fix the behavior.
The introduction of `parse_url_ex2()` has been suggested by Nikita.
[1] <http://git.php.net/?p=php-src.git;a=commit;h=81b2f3e5d9fcdffd87a4fcd12bd8c708a97091e1>
Closes GH-6399.
2cab085bb3