Win32: preserving binary compatibility with Windows XP - Vista. OpenSSL 1.1.0 and above uses BCrypt if available (Windows 7 or higher). This results in an unusable binary on older Windows versions, when building with newer Windows SDK (such as 7.0A). Using CFLAGS to define _WIN32_WINNT allows to set a desired ABI and make sure the binary works with Windows XP. To not mix with other potential CFLAGS uses, it is set in GNUmakefile.

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


cat << END >> $NGX_AUTO_CONFIG_H

#ifndef $have
#define $have  1
#endif

END