Output chain: zero size buf alerts in ngx_chain_writer(). Now we log a "zero size buf in chain writer" alert if we encounter a zero sized buffer in ngx_chain_writer(), and skip the buffer.

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


cat << END >> $NGX_AUTO_CONFIG_H

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

END