virtttest.utils_net: add restart nic and get nic attributes of windows guest

This patch adds function support restart windows guest network,
except winxp. add function to get windows nic attributes(like nic index,
netconnectionid, macaddress ans so on, you can get all support
attributes by 'wmic nic get ').

Signed-off-by: Yunping Zheng <yunzheng@redhat.com>
qemu : add mac_change support windows

This patch makes mac_change case support windows guests, except WinXP

Signed-off-by: Yunping Zheng <yunzheng@redhat.com>
qemu : Modify configure for jumbo test support windows guest

This patch make case jumbo test support windows except winxp

Signed-off-by: Yunping Zheng <yunzheng@redhat.com>
qemu: Add iperf nic multicast test

This patch using iperf test guest nic multicast, support both
linux and windows guests.

Signed-off-by: Yunping Zheng <yunzheng@redhat.com>