Kernel prepatch 4.20-rc1

Linus has released 4.20-rc1 and closed themerge window for this development cycle. "So I did debate calling it 5.0, but if we all help each other, I'msure we can count to 20. It's a nice round number, and I didn't wantto make a pattern of it. I think 5.0 happens next year, because then I*really* run out of fingers and toes."