Allowed up to two EBUSY errors from sendfile(). Fallback to synchronous sendfile() now only done on 3rd EBUSY without any progress in a row. Not falling back is believed to be better in case of occasional EBUSY, though protection is still needed to make sure there will be no infinite loop.

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


cat << END >> $NGX_AUTO_CONFIG_H

#ifndef $have
#define $have  1
#endif

END