xapi: new stunnel doesn't accept the 'compression=' argument

It's not clear whether burning dom0 CPU on compression to reduce network
bandwidth is really a good tradeoff.

Signed-off-by: David Scott <dave.scott@citrix.com>
xapi: listen on port 443

The $ACCEPT (=$2) argument will be IPv6 if the host has any kind of IPv6
enabled, even if we're not using it.

Signed-off-by: David Scott <dave.scott@citrix.com>