Fix reporting refused connections with ExtUvLoop

The underlying `epoll_wait()` reports `EPOLLOUT|EPOLLERR|EPOLLHUP` on
the affected file descriptor, which `ext-uv` emits as an error code
`EBADF` with no events attached. We explicitly re-enable all active
events on this error event to invoke the writable listener for this
condition to match other event loop implementations and successfully
detect this as a refused connection attempt. All tests are now green.

Author: clue

src/ExtUvLoop.php

@@ -294,13 +294,15 @@ private function pollStream($stream)
     private function createStreamListener()
     {
         $callback = function ($event, $status, $events, $stream) {
-            if (!isset($this->streamEvents[(int) $stream])) {
-                return;
-            }
-
-            if (($events | 4) === 4) {
-                // Disconnected
-                return;
+            // libuv automatically stops polling on error, re-enable polling to match other loop implementations
+            if ($status !== 0) {
+                $this->pollStream($stream);
+
+                // libuv may report no events on error, but this should still invoke stream listeners to report closed connections
+                // re-enable both readable and writable, correct listeners will be checked below anyway
+                if ($events === 0) {
+                    $events = \UV::READABLE | \UV::WRITABLE;
+                }
             }
 
             if (isset($this->readStreams[(int) $stream]) && ($events & \UV::READABLE)) {