Linux 5.3 rc1

It's been two weeks, and the merge window is over, and Linux 5.3-rc1
is tagged and pushed out.

This is a pretty big release, judging by the commit count. Not the
biggest ever (that honor still goes to 4.9-rc1, which was
exceptionally big), and we've had a couple of comparable ones (4.12,
4.15 and 4.19 were also big merge windows), but it's definitely up

The merge window also started out pretty painfully, with me hitting a
couple of bugs in the first couple of days. That's never a good sign,
since I don't tend to do anything particularly odd, and if I hit bugs
it means code wasn't tested well enough. In one case it was due to me
using a simplified configuration that hadn't been tested, and caused
an odd issue to show up - it happens. But in the other case, it really
was code that was too recent and too rough and hadn't baked enough.
The first got fixed, the second just got reverted.

Anyway, despite the rocky start, and the big size, things mostly
smoothed out towards the end of the merge window. And there's a lot to
like in 5.3. Too much to do the shortlog with individual commits, of
course, so appended is the usual "mergelog" of people I merged from
and a one-liner very high-level "what got merged". For more detail,
you should go check the git tree.

As always: the people credited below are just the people I pull from,
there's about 1600 individual developers (for 12500+ non-merge
commits) in this merge window.

Go test,