KVM-test: Convert drift to absolute value when comparing with threshold

If drift is a large negative, it couldn't raise exception.

Signed-off-by: Amos Kong <akong@redhat.com>


git-svn-id: http://test.kernel.org/svn/autotest/trunk@4080 592f7852-d20e-0410-864c-8624ca9c26a4
1 file changed