osx,stream: retry sending handle on EMSGSIZE error

On OSX when sending handles via `sendmsg()` it can return `EMSGSIZE` if
there isn't room in the socket output buffer to store the whole message.
In that's the case, return control to the loop and try again in the next
iteration.

Fixes: nodejs/node#14828

src/unix/stream.c

@@ -859,7 +859,16 @@ static void uv__write(uv_stream_t* stream) {
   }
 
   if (n < 0) {
-    if (errno != EAGAIN && errno != EWOULDBLOCK && errno != ENOBUFS) {
+        if (errno != EAGAIN && errno != EWOULDBLOCK && errno != ENOBUFS
+#if defined(__APPLE__)
+    /*
+     * EMSGSIZE error happens when there isn't enough room in the socket output
+     * buffer to store the whole message. If that's the case, retry in the next
+     * loop iteration.
+     */
+            && !(errno == EMSGSIZE && req->send_handle)
+#endif
+           ) {
       err = UV__ERR(errno);
       goto error;
     } else if (stream->flags & UV_STREAM_BLOCKING) {