Cancel stream if flow control window gets overflow

Previously, we did terminate session, but it did not actually cancel
streams.  Now we just cancel streams in this case.

lib/nghttp2_session.c

@@ -3779,8 +3779,8 @@ static int update_remote_initial_window_size_func(nghttp2_map_entry *entry,
   rv = nghttp2_stream_update_remote_initial_window_size(
       stream, arg->new_window_size, arg->old_window_size);
   if (rv != 0) {
-    return nghttp2_session_terminate_session(arg->session,
-                                             NGHTTP2_FLOW_CONTROL_ERROR);
+    return nghttp2_session_add_rst_stream(arg->session, stream->stream_id,
+                                          NGHTTP2_FLOW_CONTROL_ERROR);
   }
 
   /* If window size gets positive, push deferred DATA frame to
@@ -3831,8 +3831,8 @@ static int update_local_initial_window_size_func(nghttp2_map_entry *entry,
   rv = nghttp2_stream_update_local_initial_window_size(
       stream, arg->new_window_size, arg->old_window_size);
   if (rv != 0) {
-    return nghttp2_session_terminate_session(arg->session,
-                                             NGHTTP2_FLOW_CONTROL_ERROR);
+    return nghttp2_session_add_rst_stream(arg->session, stream->stream_id,
+                                          NGHTTP2_FLOW_CONTROL_ERROR);
   }
   if (!(arg->session->opt_flags & NGHTTP2_OPTMASK_NO_AUTO_WINDOW_UPDATE) &&
       stream->window_update_queued == 0 &&

tests/nghttp2_session_test.c

@@ -4610,8 +4610,8 @@ void test_nghttp2_submit_settings_update_local_window_size(void) {
   CU_ASSERT(0 == nghttp2_session_on_settings_received(session, &ack_frame, 0));
 
   item = nghttp2_session_get_next_ob_item(session);
-  CU_ASSERT(NGHTTP2_GOAWAY == item->frame.hd.type);
-  CU_ASSERT(NGHTTP2_FLOW_CONTROL_ERROR == item->frame.goaway.error_code);
+  CU_ASSERT(NGHTTP2_RST_STREAM == item->frame.hd.type);
+  CU_ASSERT(NGHTTP2_FLOW_CONTROL_ERROR == item->frame.rst_stream.error_code);
 
   nghttp2_session_del(session);
   nghttp2_frame_settings_free(&ack_frame.settings, mem);