qemu.qemu_vm: support vhostfd in netdev.

vhostfd only works when vhost on.
add enable_vhost parameter. set default value to 'yes'
Signed-off-by: Feng Yang <fyang@redhat.com>
utils_libvirtd: if libvirt is not availible in host, No error, but a warning.

Signed-off-by: yangdongsheng <yangds.fnst@cn.fujitsu.com>
virt: modify libvirtd_status() to libvirtd_is_running()

Signed-off-by: Li Yang <liyang.fnst@cn.fujitsu.com>
virttest.aexpect: Fix old class Spawn definition.

The base class Spawn for ShellSession was defined in old way(class Spawn).
Then we can not use super() for inherited classes:
TypeError: super() argument 1 must be type, not classobj

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
README.rst: add basic troubleshooting instructions

As suggested by Juan Quintela.

CC: Juan Quintela <quintela@redhat.com>
Signed-off-by: Cleber Rosa <crosa@redhat.com>
virttest.env_process: Fix postprocess logging

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
virt: Aexpect server logging and startup lock adjustment

* Removed possibly contentious client & server locking
  (lock-client-starting)
* Removed client dependence on server stdout
* Made server close stdin/out/err to avoid pipe flush problems
* Add support for empty reader list
* Added server logging
* Made server lock at earliest possible point
* Added exception handling to server
* Added Spawn.__init__() server timeout
* Fixed ignored exception in Spawn.__del__

Signed-off-by: Chris Evich <cevich@redhat.com>