add support for ipv6 address in choose_vnc_display function

getting the port from the latest field, not the first one.
fix suggested by Nickolai Zeldovich. close bug #231

Signed-off-by: Vincent Hanquez <vincent@xensource.com>

tools/python/xen/xm/create.py

@@ -673,7 +673,7 @@ def choose_vnc_display():
             # Local port is field 3.
             y = x.split()[3]
             # Field is addr:port, split off the port.
-            y = y.split(':')[1]
+            y = y.split(':')[-1]
             r.append(int(y))
         return r