Upstream: u->conf->preserve_output flag. The flag can be used to continue sending request body even after we've got a response from the backend. In particular, this is needed for gRPC proxying of bidirectional streaming RPCs, and also to send control frames in other forms of RPCs.

# Copyright (C) Igor Sysoev
# Copyright (C) Nginx, Inc.


cat << END >> $NGX_AUTO_CONFIG_H

#ifndef $have
#define $have  $value
#endif

END