Cider Isn't Darwin Emulation, Really

Explicitly return `ENOSYS` for the `clonefileat` and `fclonefileat` syscalls master

We were already returning ENOSYS in `__unknown_syscall`, but that prints a message saying the syscall is unimplemented. This version is a valid implementation of the syscalls (it's not guaranteed to be available on all systems).


+24
4 changed files