[HAVE_CONFIG_H]: Include <config.h>.

[HAVE_CONFIG_H]: Include <config.h>.
Conditionalize inclusion of <sys/param.h>.
Conditionalize inclusion of <include/sys/stat.h> vs <sys/stat.h>.
Include autoconf-recommended block of dirent/NAMELEN-related
definitions and includes.  Use NAMLEN throughout, rather than
_D_EXACT_NAMLEN.
[_LIBC] (close, closedir, fchdir, open, opendir): Define.
[_LIBC] (readdir, tdestroy, tfind, tsearch): Define.
Remove `__' prefix from all uses of the above.  This will help
to merge *BSD changes.
[!_LIBC] (internal_function): Define.
[! _LIBC && ! LSTAT_FOLLOWS_SLASHED_SYMLINK]: Define lstat.
(__set_errno): Define if not already defined.