Add a definition for the extended_socket_class policy capability used
to enable the use of separate socket security classes for all network
address families rather than the generic socket class.  The capability
also enables the use of separate security classes for ICMP and SCTP
sockets, which were previously mapped to rawip_socket class.  Add
definitions for the new socket classes and access vectors enabled by
this capability.  Add the new socket classes to the socket_class_set
macro, and exclude them from webview_zygote domain as with other socket
classes.

Allowing access by specific domains to the new socket security
classes is left to future commits.  Domains previously allowed
permissions to the 'socket' class will require permission to the
more specific socket class when running on kernels with this support.

The kernel support will be included upstream in Linux 4.11.  The
relevant kernel commits are da69a5306ab92e07224da54aafee8b1dccf024f6
("selinux: support distinctions among all network address families"),
ef37979a2cfa3905adbf0c2a681ce16c0aaea92d ("selinux: handle ICMPv6
consistently with ICMP"), and b4ba35c75a0671a06b978b6386b54148efddf39f
("selinux: drop unused socket security classes").

This change requires selinux userspace commit
d479baa82d67c9ac56c1a6fa041abfb9168aa4b3 ("libsepol: Define
extended_socket_class policy capability") in order to build the
policy with this capability enabled.  This commit is already in
AOSP master.

Test: policy builds

Change-Id: I788b4be9f0ec0bf2356c0bbef101cd42a1af49bb
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>

Divide policy into public and private components.  This is the first
step in splitting the policy creation for platform and non-platform
policies.  The policy in the public directory will be exported for use
in non-platform policy creation.  Backwards compatibility with it will
be achieved by converting the exported policy into attribute-based
policy when included as part of the non-platform policy and a mapping
file will be maintained to be included with the platform policy that
maps exported attributes of previous versions to the current platform
version.

Eventually we would like to create a clear interface between the
platform and non-platform device components so that the exported policy,
and the need for attributes is minimal.  For now, almost all types and
avrules are left in public.

Test: Tested by building policy and running on device.

Change-Id: Idef796c9ec169259787c3f9d8f423edf4ce27f8c