Streams will be freed in an unpredictable order during shutdown.
Ignore explicit calls to php_stream_close() entirely to avoid
use-after-free -- instead let the stream resource destructor
deal with it. We have to account for a few special cases:
* Enclosed streams should be freed, as the resource destructor
will forward to the enclosing stream.
* Stream cookies also directly free streams, because we delegate
to the cookie destruction if one exists.
* Mysqlnd also directly frees streams, because it explicitly
removes stream resources (because mysqlnd!)