kvm tools: Make tcp between guest/host virtual ip work in UIP mode

kvm tools: Make tcp between guest/host virtual ip work in UIP mode

This pach makes tcp between 'guest ip' and 'host virtual ip' work in UIP mode.
(The defulat guest ip is 192.168.33.15, host virtual ip is 192.168.33.1)

  guest$ wget http://192.168.33.1/file
  guest$ ssh 192.168.33.1

Without this patch, user has to figure out the ip address of host's
interface (e.g. eth0) and use that ip address to access host.

With this patch, user can simply use the virtual host ip.

Signed-off-by: Asias He <asias.hejun@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>