Split DNS

Split DNS

In AnyConnect the server seems to offer an X-CSTP-Split-DNS: header,
which can appear multiple times, with search domains for the client to
use. I'm exporting these in $CISCO_SPLIT_DNS, space-separated.
(A. Borneo: in recent openconnect it is now comma-separated)

I see that there's an ISAKMP_MODECFG_ATTRIB_CISCO_SPLIT_DNS, but we
don't seem to *do* anything with it. Like the IPv6 attributes which we
also ignore, just make vpnc clear the environment variable.

We really ought to make vpnc *support* these, given that we know how to
recognise them. But that's left as an exercise for someone who actually
has access to a server.

A. Borneo:
This patch completes Evan Broder's one.

Author: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
git-svn-id: https://svn.unix-ag.uni-kl.de/vpnc/trunk@533 315857ad-0bdb-0310-b42e-dec37551a5f0