Linux 4.20 rc4

The patch stats this week look a little bit more normal than last time,
probably simply because it's also a normal-sized rc4 rather than the
unusually small rc3.

So this time around, about 60% of the patch is drivers (networking,
HID, gpu, usb, mtd..) which is the usual distribution. The rest being
a random mix of networking, filesystem fixes, arch updates,
Documentation etc. And some fixes to the new xarray code.

Nothing looks particularly odd or scary, although we do have some
known stuff still pending. For example, the STIBP fixes are still
being discussed and fine-tuned and haven't been merged yet. And
there's a few mm fixes being talked about. Nothing that should keep
people from testing the 4.20 rc's, though, so go out and test.

One thing I did forget to mention last rc, but did come up in some of
the pull request threads, and that people might have noticed that way:
I've stopped doing the manual pull request acknowledgement emails,
because Konstantin's automation to do it has gone live and is working
well. It's worth pointing out, though, that the automation only works
for pull requests that have been cc'd to mailing lists that are being
tracked by the lore.kernel.org archives, and have an email address
that matches "linux-*". So that's obviously mainly LKML, but it does
trigger for linux-block too, for example.

The reason I'm mentioning it is that if you're not seeing the pull
request automation emails, it might be because you didn't cc a list
that is getting tracked..