SSL: include <openssl/hmac.h>. This header carries the definition of HMAC_Init_ex(). In OpenSSL this header is included by <openssl/ssl.h>, but it's not so in BoringSSL. It's probably a good idea to explicitly include this header anyway, regardless of whether it's included by other headers or not.

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


cat << END >> $NGX_AUTO_CONFIG_H

#ifndef $have
#define $have  0
#endif

END