Core: fixed stderr redirection on win32 in ngx_reopen_files(). On win32 stderr was not redirected into a file specified by "error_log" while reopening files. Fix is to use platform-independent functions to work with stderr, as already used by ngx_init_cycle() and main() since rev. d8316f307b6a.

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


cat << END >> $NGX_AUTO_CONFIG_H

#ifndef $have
#define $have  0
#endif

END