Upstream: handling of certificates specified as an empty string. Now, if the directive is given an empty string, such configuration cancels loading of certificates, in particular, if they would be otherwise inherited from the previous level. This restores previous behaviour, before variables support in certificates was introduced (3ab8e1e2f0f7).

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


cat << END >> $NGX_AUTO_CONFIG_H

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

END