Kernel prepatch 4.15-rc3

The 4.15-rc3 kernel prepatch is out."I'm not thrilled about how big the early 4.15 rc's are, but rc3 isoften the biggest rc because it's still fairly early in thecalming-down period, and yet people have had some time to startfinding problems. That said, this rc3 is big even by rc3 standards.Not good." 489 changesets were merged since 4.15-rc2.