utils_test: use data_dir in run_virt_sub_test function.

Originally, run_virt_sub_test function will only search the
top level of directory in sub test, such as virt/libvirt/tests/.
But in libvirt-tests, lots of test module is not in this location.
So use data_dir in this function to search test modules for us.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
libvirt-bench: Add test for switching domstate of vms in groups.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
libvirt_bench: optimize the log in libvirt_bench_domstate_switch_in_loop.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
Merge pull request #1029 from yangdongsheng/libvirt_bench

Libvirt bench