* io/Makefile (routines): Add mknodat, xmknodat, mkdirat, mkfifoat.

* io/Makefile (routines): Add mknodat, xmknodat, mkdirat, mkfifoat.

	(static-only-routines): Add mknodat.
	* io/Versions [GLIBC_2.4]: Add mkdirat, mkfifoat, __xmknodat.
	* io/sys/stat.h: Declare mkditat, mknodat, mkfifoat, __xmknodat.
	Define mknodat inline function.
	* include/sys/stat.h: Add hidden proto for __xmknodat.
	* sysdeps/generic/mkdirat.c: New file.
	* sysdeps/generic/mkfifoat.c: New file.
	* sysdeps/generic/mknodat.c: New file.
	* sysdeps/generic/xmknodat.c: New file.
	* sysdeps/unix/mkfifoat.c: New file.
	* sysdeps/unix/sysv/linux/mkdirat.c: New file.
	* sysdeps/unix/sysv/linux/xmknodat.c: New file.

	* sysdeps/generic/xmknod.c: Add one more parameter check.