Update headers for Linux 3.15

[Roland McGrath]

> * renameat2 - this relates to the general question of when glibc
>   should provide bindings to Linux kernel syscalls, which requires
>   someone to take the lead on producing an analysis with reference to
>   the various previous threads on this subject, seeking consensus on
>   principles for when to provide such bindings, and then adding
>   bindings for whatever syscalls meet the principles but don't
>   currently have them.

A new kernel feature like this can be addressed in two ways.  What
you've described is one of them.  The other is to decide that the
feature is worthy of being a first-class part of the GNU API, and
add support for it specifically in libc (including an ENOSYS stub
that non-Linux configurations will use until and unless the feature
is implemented elsewhere).  Off hand I am not particularly inclined
to argue for such treatment for renameat2.  But the general point
stands for how to contemplate such issues as they arise.


Thanks,
Roland