Linux 4.16 rc4

Hmm. A reasonably calm week - the biggest change is to the 'kvm-stat'
tool, not any actual kernel files.

But there's small changes all over, with architecture updates (x86,
s390, arm, parisc) and drivers (media, md, gpu, sound) being the bulk
of it. But there's some filesystem fixes (mostly btrfs),
documentation updates etc too.

Go test,