libseccomp : high level interface to Linux seccomp filter ( https://github.com/seccomp/libseccomp )
libunwind : Portable and efficient API to determine the call-chain of a program ( https://savannah.nongnu.org/projects/libunwind )
Add an ebuild in portage :
The ebuild is now in the portage tree.
You can also use layman : emerge layman then layman -a gnux32
For Paludis use this rsync : rsync://gentoo.zugaina.org/gnux32-portage
If you have a problem : ycarus(-at-)zugaina.org