winsock: Clear the held mask with the requested events so that they can be signaled.
diff --git a/server/sock.c b/server/sock.c
index ce63932..c1a7a8d 100644
--- a/server/sock.c
+++ b/server/sock.c
@@ -814,6 +814,7 @@
                                                 FILE_WRITE_ATTRIBUTES, &sock_ops))) return;
     old_event = sock->event;
     sock->mask    = req->mask;
+    sock->hmask   &= ~req->mask; /* re-enable held events */
     sock->event   = NULL;
     sock->window  = req->window;
     sock->message = req->msg;