vcpu->running is duplicated with THREAD_STS_RUNNING status of thread
object. Introduce an API sleep_thread_sync(), which can utilize the
inner status of thread object, to do the sync sleep for zombie_vcpu().
Tracked-On: #5057
Signed-off-by: Conghui Chen <conghui.chen@intel.com>
Reviewed-by: Shuo A Liu <shuo.a.liu@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>