Cache: multiple variants of a resource now can be stored. If a variant stored can't be used to respond to a request, the variant hash is used as a secondary key. Additionally, if we previously switched to a secondary key, while storing a response to cache we check if the variant hash still apply. If not, we switch back to the original key, to handle cases when Vary changes.

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


cat << END >> $NGX_AUTO_CONFIG_H

#ifndef $have
#define $have  0
#endif

END