* modules/chdir-long, modules/openat: New files.

* modules/chdir-long, modules/openat: New files.
* modules/save-cwd (Depends-on): Depend on chdir-long.
(Makefile.am): Remove lib_SOURCES; now handled by AC_LIBSOURCES.
* lib/save-cwd.c: Include "save-cwd.h" before other include files.
(O_DIRECTORY): Remove; not needed here, since "." must be
a directory.  All uses removed.
(save_cwd): Use __sgi || __sun, not sun || __sun.  __sun is
universal on Suns, and we also need to test for IRIX.
Revamp code to use 'if' rather than '#if'.
Avoid unnecessary comparison of cwd->desc to 0.

Change the name of the robust chdir function from chdir to chdir_long.
* lib/save-cwd.c: Include chdir-long.h rather than chdir.h.
(restore_cwd): Use chdir_long, not chdir.
* lib/chdir-long.c: Renamed from chdir.c.
* lib/chdir-long.h: Renamed from chdir.h.
[!defined PATH_MAX]: Define chdir_long to chdir on systems like the Hurd.

* m4/chdir-long.m4, openat.m4: New files.
* m4/save-cwd.m4 (gl_SAVE_CWD): Add AC_LIBSOURCES for save-cwd.c,
save-cwd.h.  Add AC_LIBOBJ for save-cwd.