Allow sandbox to be initialised without needing access to /proc

[GoogleCodeExporter]

This is a less specific version of issue 9.

We would like to be able to initialise the seccomp sandbox without
needing access to /proc/self/maps, so that we don't have to open a
hole in the SUID sandbox to get access to /proc.

Original issue reported on code.google.com by mseaborn@chromium.org on 18 Oct 2010 at 1:27