Add 'ioctl' syscall to Linux.

    It's going to be needed by BPF. Note, I am not sure about how the
    ABI will work for varargs, and the code may need revisiting and/or
    compatibility shims.

    I'm with the plan 9 folks: Fuck ioctl.
Merge branch 'master' of git+ssh://mimir.eigenstate.org/git/ori/mc