Changes to forwarding for wifi calling.

1. Support multiple forwarding requests. Keep track of all
   requests inside TetherController, and enable system
   forwarding any time there is more than one active request.
2. Enable both IPv4 and IPv6 forwarding.

Bug: 19500693
Change-Id: Ic81bae7b399bc6ebf6a63de4bcd341885638dfa4
3 files changed
tree: d2ac9ee8f84812a2e32c7f63c693e54d9eef9a55
  1. client/
  2. include/
  3. server/