init.rc: setup qtaguid group ownership of ctrl and stat files

This will help get rid of android_aid.h in the kernel.
The group of the proc entries will be used in place of the default
values picked up by the xt_qtaguid netfilter module
(AID_NET_BW_STATS, AID_NET_BW_ACCT).
This change has no effect until the matching kernel changes are submitted.

https://android.googlesource.com/platform/system/core/+/3e54aabc63535572242477fadbf13ec42b06649e%5E%21/
init.rc: allow IPPROTO_ICMP support

Allow userspace programs to create IPPROTO_ICMP sockets.

This socket type allows an unprivileged program to safely
send ICMP_ECHO messages and receive the corresponding
ICMP_ECHOREPLY messages, without relying on raw sockets or
setuid programs.

Please see http://lwn.net/Articles/443051/ for details.

In particular, this allows us to use a version of ping
which doesn't have any capabilities
(https://android-review.googlesource.com/52072).
In addition, this allows us to safely implement an IPv4 ICMP
based version of InetAddress.isReachable()
(https://code.google.com/p/android/issues/detail?id=20106)

https://android.googlesource.com/platform/system/core/+/be341cc348257a07c68bcbfdc526835d49283329%5E%21/