Enable unit & acceptance testing for HPUX.
Make chroot contain device files.

HPUX does not have a devfs, and copying the files as device files
seems top work ok there. This way we will have access to things like
the random device.

Also make sure rsync honors special files.
HPUX does not have /proc, so make mounting a noop inside chroot.
Avoid error if unmount of /proc fails.

HPUX does not have /proc, and even if a filesystem does have it, if
the error triggers it disturbs the fetching of the test logs, and
there is nothing we can do about a failed unmount anyway.