Core: added realpath() checking when testing PID files. This ensures that if the PID file path is changed, yet resolves to the same file via symbolic links, trying to recreate the PID file won't remove it. In particular, this resolves issues as observed on Linux systems with "/var/run/nginx.pid" changed to "/run/nginx.pid".

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


cat << END >> $NGX_AUTO_CONFIG_H

#ifndef $have
#define $have  1
#endif

END