error code as well as errno. Use throughout where errno is set from
NT status.
(set_errno): Evaluate val only once.
* fhandler_disk_file.cc (fhandler_base::fstat_by_handle): Fix typo in
debug output.
* fhandler_mem.cc (fhandler_dev_mem::open): Rely on
__seterrno_from_nt_status setting Win32 error code in debug output.
* fhandler_proc.cc (format_proc_uptime): Ditto.
(format_proc_stat): Ditto.
* fhandler_process.cc (format_process_stat): Ditto.
* sysconf.cc (sysconf): Ditto.