iputils: set the permissions with IPUTILS_PERMISSIONS

iputils: set the permissions with IPUTILS_PERMISSIONS

... for arping, clockdiff and ping. These require root permission for
socket(). Upstream solution (script setcap-setuid.sh) requires
setcap binary on the host and cap_net_raw+ep + libcap, or setting
setuid root executable (which is dangerous). Neither would work anyway
since we install as non-root user.

This restores behavior used for version s20180629. We used to setuid the
ping and traceroute6 programs. traceroute6 is no longer built since the
bump to s20190515, but now arping and clockdiff are built, and these
need setuid as well. So enable setuid on arping, clockdiff and ping.

Signed-off-by: Petr Vorel <petr.vorel@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>