HTTP/2: lingering close after GOAWAY. After sending the GOAWAY frame, a connection is now closed using the lingering close mechanism. This allows for the reliable delivery of the GOAWAY frames, while also fixing connection resets observed when http2_max_requests is reached (ticket #1250), or with graceful shutdown (ticket #1544), when some additional data from the client is received on a fully closed connection. For HTTP/2, the settings lingering_close, lingering_timeout, and lingering_time are taken from the "server" level.

--- a/src/http/v2/ngx_http_v2.h
+++ b/src/http/v2/ngx_http_v2.h
@@ -157,6 +157,8 @@ struct ngx_http_v2_connection_s {
     ngx_uint_t                       last_sid;
     ngx_uint_t                       last_push;
 
+    time_t                           lingering_time;
+
     unsigned                         closed_nodes:8;
     unsigned                         settings_ack:1;
     unsigned                         table_update:1;