libseccomp needs aarch64 port

[Riku Voipio]

libseccomp is used for sandboxing by qemu, lxc and tor. seccomp remains rather unpopular, and this it is just an optional dependency for the tools. We might want to support for Aarch64 for sake of completeness.

high level interface to Linux seccomp filter
 libseccomp library provides a high level interface to constructing, analyzing
 and installing seccomp filters via a BPF passed to the Linux Kernel's
 prctl() syscall.

[Marcin Juszkiewicz (hrw)]

I made a port. Patches sent to upstream ML:

    https://sourceforge.net/p/libseccomp/mailman/message/32380684/

    https://sourceforge.net/p/libseccomp/mailman/message/32380659/

[Riku Voipio (riku-voipio)]

maintainer said that this code needs seccomp code included in kernel - is this in linus's upstream no, or should I poke some kernel people?