Kernel prepatch 5.1-rc1

Linus has released 5.1-rc1 and closed themerge window for this development cycle. "A somewhat recentdevelopment is how the tools/testing/ updates have been quite noticeablelately. That's not new to the 5.1 merge window, it's been going on for awhile, but it's maybe just worth a mention that we have more new selftestchanges than we have architecture updates, for example. The documentationsubdirectory is also quite noticeable."