Linux 4.13 rc2

Things are chugging along, and we actually had a reasonably active rc2.

Normally rc2 is really small because people are taking a breaher and
haven't started finding bugs yet, but this time around we have a
bigger-than-average rc2. We'll just have to see how that translates to
the rest of the release cycle, but I suspect it's just the normal
variability in this thing (and because I released -rc1 one day early,
I guess rc2 was one day longer than usual despite the normal Sunday

Changes all over, although the diffstat is dominated by the new
vboxvideo staging driver. I shouldn't have let it through, but Greg,
as we all know, is "special". Also, Quod licet Iovi, and all that jazz
- Greg gets to occasionally break some rules.

If you just ignore that new staging driver, the remainder is still
about half driver patches (networking, rdma, scsi, usb). The rest
looks normal too: architecture updates (x86, sparc, powerpc),
filesystem (nfs, overlayfs, misc), networking and core kernel. And
some new bpf testcode.

Time for some more testing, people. You know the drill.