Instead of creating a QIOChannelSocket directly for the migration
server socket, use a QIONetListener. This provides the ability
to listen on multiple sockets at the same time, so enables
full support for IPv4/IPv6 dual stack.

For example,   '$QEMU -incoming tcp::9000' now correctly listens
on both 0.0.0.0 and :: at the same time, instead of only on 0.0.0.0.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <20180312141714.7223-1-berrange@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>