sysctl value `net.ipv4.ping_group_range` can be used for allowing `ping`
command without `CAP_NET_RAW` capability.
e.g. `net.ipv4.ping_group_range="0 42"` to allow ping for users with
GID 0-GID 42.
This sysctl value was introduced in kernel 3.0 and has been namespaced
since its birth.
c319b4d76b (diff-5b536a7a92abed603bbb4caa61613270R57)
Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>