Let SocketClient users write binary data to clients.

This is a dependency for the DNS proxy CLs.

This CL also adds a new socket for the netd process to inherit which
is owned by the inet group.  (so only apps with the INTERNET
permission can use the DNS proxy...)

Change-Id: I8a51924e0ed56c6066f77e6f1b02d39bdadac51e
3 files changed