Update libwebsockets to 3.1 (plus UWP patch)

thirdparty/libwebsockets/lib/event-libs/poll/private.h

@@ -0,0 +1,23 @@
+/*
+ * libwebsockets - small server side websockets and web server implementation
+ *
+ * Copyright (C) 2010 - 2018 Andy Green <andy@warmcat.com>
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation:
+ *  version 2.1 of the License.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ *  MA  02110-1301  USA
+ *
+ */
+
+extern struct lws_event_loop_ops event_loop_ops_poll;