Upstream: do not unnecessarily create per-request upstreams. If proxy_pass (and friends) with variables evaluates an upstream specified with literal address, nginx always created a per-request upstream. Now, if there's a matching upstream specified in the configuration (either implicit or explicit), it will be used instead.

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


cat << END >> $NGX_AUTO_HEADERS_H

#ifndef $have
#define $have  1
#endif

END