Do not add any "Connection" headers for "upgrade" connections.

ChangeLog

@@ -1,3 +1,6 @@
+Thu May 11 14:24:00 MSK 2017
+	Do not add any "Connection" headers for "upgrade" connections. -EG
+
 Wed May 10 23:09:00 MSK 2017
 	Resume resuming connection before other processing in external polling 
 	mode. -EG

src/microhttpd/connection.c

@@ -1205,6 +1205,9 @@ build_header_response (struct MHD_Connection *connection)
              (connection->read_closed) ||
              (MHD_CONN_MUST_CLOSE == connection->keepalive)) &&
            (! response_has_close) &&
+#ifdef UPGRADE_SUPPORT
+           (NULL == connection->response->upgrade_handler) &&
+#endif /* UPGRADE_SUPPORT */
            (0 == (connection->response->flags & MHD_RF_HTTP_VERSION_1_0_ONLY) ) )
         must_add_close = MHD_YES;