disable cases used netsh on WinXP

As WinXP is buggy on 'netsh interface set' sub commands,
not worth to fix on such out of date OS, disabling.

Signed-off-by: Xiaoqing Wei <xwei@redhat.com>
Merge pull request #973 from xiaoqing-wei/netsh_disable_WinXP

disable cases used netsh on WinXP