KVM test: unattended_install: Introduce wait_no_ack param

KVM test: unattended_install: Introduce wait_no_ack param

Some distros such as OpenSUSE won't let the install test to
communicate the guest ACK for some weird reason [1], this commit
modifies the unattended_install test introducing a wait_no_ack
param that will skip the ACK check, and break the unattended
install loop when the machine turns off itself (directive halt
on OpenSUSE and SLES unattended file).

Other distros shouldn't be affected by this change, their
install behavior was kept the same.

[1] Tried several ways of transmitting the ACK by means of chroot
scripts, no way. In the end of the day, I was short on time to
spend too much of it figuring out a way to do it, hence the
wait_no_ack param was born. I really could use some help from the
guys that introduced OpenSUSE and SLES support to kvm autotest.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
git-svn-id: svn://test.kernel.org/autotest/trunk@5320 592f7852-d20e-0410-864c-8624ca9c26a4