Re: [libvirt] [PATCH] qemu: Fix backwards compatibility of S390 guests

This patch reverts commit 73e4e10e62e4b1aea64b317be96af5e5488007d7 and thereby disabling the panic device autogeneration for S390 guests. In addition tests are patched as well. The reverted commit breaks backwards compatibility of S390 guests. As an example: A domain xml without a panic device can successfully be used to define on two hosts with different libvirt versions. Using this domain xml to define a domain on a host with libivrt v1.3.5 makes it impossible to migrate the domain to a host with libvirt v1.3.4 or older since libvirt v1.3.5 automatically added a panic device with model s390 which libvirt v1.3.4 or older rejects as unknown model.