RFC: adding a 'version' flag process to kernel development in a non-destructive manner

Yeah, but some of the comments in this thread have been talking about
dropping old syscalls and breaking userspace compatibility. Personally I
don't think anyone would care if, say, a.out and all syscalls obsoleted
before the ELF transition stopped working (it happens regularly already
for many kernel releases at a time: Alan Cox was the last person I've
heard of who runs stuff on libc2 and libc3, and even he's stopped now),
but breaking anything from the ELF era is probably a mistake.