factoring out "at" syscalls common code in nlookup

[Matthew Dillon]

:Hello,
:
:As part of implementing the at family of syscalls (openat(),
:fstatat(), ...), I propose to put the common code handling the file
:descriptor argument in the namecache as shown in the patch below.
:
:Any objection?
:
:Cheers,
:Nicolas

    Looks pretty good but what is nl_atfp used for?  The fp has to be
    held anyway, I know, but I think I'd rather it be done explicitly
    in the system calls like it is already.

						-Matt