* posix/bits/unistd.h (__readlinkat_chk): New prototype.

* posix/bits/unistd.h (__readlinkat_chk): New prototype.

	(__readlinkat_alias): New alias.
	(readlinkat): New inline function.
	* include/unistd.h (readlinkat): Add libc_hidden_proto.
	* sysdeps/unix/sysv/linux/readlinkat.c (readlinkat): Add
	libc_hidden_def.
	* io/readlinkat.c (readlinkat): Likewise.
	* debug/readlinkat_chk.c: New file.
	* debug/Makefile (routines): Add readlinkat_chk.
	* debug/Versions (libc): Export __readlinkat_chk@@GLIBC_2.5.
	* debug/tst-chk1.c (do_test): Add readlinkat tests.

	* nis/nss_nisplus/nisplus-netgrp.c: Cleanups.
	code is possible.  Move compatibility code in .text.compat section.
	over gaih array.  There is only one function to call in the moment.