The IBM hypervisor distro "KVM for IBM z Systems" gets discontiued,
like announced in March 2017 [1]. The key dates are:
* 03/2017: announcement
* 08/2017: the last day to order (EOM)
* 03/2018: the End of Service (EOL)
As the CI which tests OpenStack with KVM on IBM Z doesn't rely on this
distro anymore and EOM has reached, we remove the Devstack support for
this distro.
This basically reverts commit a5ea08b of Dec 2015.
NOTE: This doesn't affect other distros which have KVM on Z support.
References:
[1] FAQ for KVM for IBM z Systems Delivery Strategy Change
https://www-01.ibm.com/common/ssi/cgi-bin/ssialias?htmlfid=ZSQ03110USEN&
Change-Id: I009ae4779588615633bff81d0c47a1b879ec9279
b8335eebe8