Push IPv6 addresses to libjingle PortAllocator.

Currently we have disabled IPv6 support in libjingle, but
there is effort going on to support it. This is the one of the first step in that process.

TBR=sergeyu@chromium.org
BUG=https://code.google.com/p/webrtc/issues/detail?id=1406

Review URL: https://codereview.chromium.org/30193002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233473 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 233473