examples/vm_power_manager: fix libvirt dependency check

examples/vm_power_manager: fix libvirt dependency check

vm_power_manager utilize libvirt API virDomainGetVcpuPinInfo to
retrieve domU vcpu information. This API is implemented from version 0.9.3.
Suse11 SP3 32bit default libvirt version is 0.8.8.

examples/vm_power_manager/channel_manager.c:
channel_manager.c:117:3: error: implicit declaration of function
'virDomainGetVcpuPinInfo'

Check and skip it from examples or raise an error when trying to compile
without libvirt or with a too old libvirt.

Fixes: e8ae9b662 ("examples/vm_power: channel manager and monitor in host")

Signed-off-by: Marvin Liu <yong.liu@intel.com>
Signed-off-by: Thomas Monjalon <thomas.monjalon@6wind.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>