Bug#1030545: qemu: qemu-img and qemu-system-s390x hang on s390x

[Michael Tokarev]

In the build logs for libguestfs, I see last successful builds were done
on 5.10.0-20-s390x kernel, and on 5.10.0-21-s390x, all builds fails.
5.10.0-21-s390x is the one running on zelenka too.

It looks to me like a kernel issue..

/mjt