Moving the kernel to modern C

In Rust, it can move the lifetime of a variable around. So if I have some code that needs to live for the outer scope, but is only "known" in some nested place, I can use `let somename;` on a block in the right place, initialize it where the data is available, and continue on. I've used this before to keep a string alive long enough for a context where it may have been either allocated (and therefore need a place to hang its destructor) or came from some other string that lived longer than the function anyways.