iputils: fix ping and traceroute6 executable permissions

The iputils executables are installed without the setuid bit set,
which prevents some programs from working.

This patch adds a permission table to fix the permissions of the ping
and traceroute6 executables.

Signed-off-by: Einar Jon Gunnarsson <tolvupostur@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>