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) Nginx, Inc.


if [ $USE_THREADS = YES ]; then

    if [ "$NGX_PLATFORM" = win32 ]; then
        cat << END

$0: --with-threads is not supported on Windows

END
        exit 1
    fi

    have=NGX_THREADS . auto/have
    CORE_DEPS="$CORE_DEPS $THREAD_POOL_DEPS"
    CORE_SRCS="$CORE_SRCS $THREAD_POOL_SRCS"
    CORE_LIBS="$CORE_LIBS -lpthread"
    NGX_LIBPTHREAD="-lpthread"
fi