tests.netperf: Update iptables stop command to ignore fail status

In some host 'service iptables stop' command exit with error code 5.
It will fail our case.

Signed-off-by: Feng Yang <fyang@redhat.com>
shared.cfg.guest-os.Windows: Ignore post_cmd status in multi_disk case

Signed-off-by: Feng Yang <fyang@redhat.com>
Merge pull request #654 from ypu/cpumodel

virttest.utils_misc: Add cpu model Opteron_G5 to get_host_cpu_models
env_process: preprocess_vm start_vm fix.

(1). Introduce a param named "kill_vm_before_test".
(2). Fix when restart_vm=yes.
(3). Fix when vm need to paused.

Signed-off-by: yangdongsheng <yangds.fnst@cn.fujitsu.com>
Add kill_vm_before_test=no in base.cfg

Signed-off-by: yangdongsheng <yangds.fnst@cn.fujitsu.com>
Merge pull request #577 from FengYang/fix

tests.netperf: Update iptables stop command to ignore fail status.
virttest.env_process: Remove unused import libvirt_vm

Signed-off-by: Yiqiao Pu <ypu@redhat.com>