Include ping6 in userdebug builds.

Also require that the user be root or have Internet
permission, like we do for IPv4.

Change-Id: I8ab8350885548ab83d5198adee912137b36d7a8d
Merge "Include ping6 in userdebug builds."
Merge tag 'android-4.3_r2.1' of https://android.googlesource.com/platform/external/ping6 into sm-jb-mr2

Android 4.3 release 2.1

Signed-off-by: Paul Beeler <sparksco@gmail.com>