[$] A safer kmalloc() for 7.0

A pull request that touches over 8,000 files, changing over 20,000 lines ofcode in the process, is (fortunately) not something that happens every day.It did happen at the end of the 7.0 merge window, though, when LinusTorvalds mergedan extensive set of changes by Kees Cook to the venerable kmalloc() API (andits users). As a result of that work, though, the kernel has a new set oftype-safe memory-allocation functions, with a last-minute bonus change tomake the API a little easier to use.