Kernel prepatch 6.0-rc4

The 6.0-rc4 kernel prepatch is out fortesting. "We're up to rc4, and things mostly still look fairlynormal".

Beyond the usual fixes, 6.0-rc4 includes one feature change: a hook to allowsecurity modules to control access to the io_uring command pass-throughmechanism. See this article for thebackground behind this late-arriving change.