libvirt.test: Add abnormal resource test for some commands

These testcases test if commands executed succeed when
resource becomes to abnormal, like lack disk, cpu disable.

Signed-off-by: Li Yang <liyang.fnst@cn.fujitsu.com>
@yumingfei, You are right, I propose `TestNAError` because my failure is caused by missing `gcc  `package. The best practice should be check the availability of `gcc` first, raise a `TestNAError` if not found. Then compile the file, raise a `TestError` if something bad happens.