Cleanup: Remove the support for IPv4 and IPv6 addressing types in the SOCKS5 implementation.

      This is no longer used by chrome, and it is unlikely that embedders would want to use this.
The default will just use the DOMAIN addressing type.

BUG=29914

Review URL: http://codereview.chromium.org/507048

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@34928 0039d316-1c4b-4281-b951-d872f2087c98