Revert "contrib/vhost-user-blk: fix the compilation issue"

Commit a56de056 squashed the following two unrelated commits
at once:

- "contrib/vhost-user-blk: fix the compilation issue"
  (Message-Id: 1547615970-23545-2-git-send-email-changpeng.liu@intel.com)
- "i386/kvm: ignore masked irqs when update msi routes"
  (Message-Id: 20190116030815.27273-5-peterx@redhat.com)

While the git history remains bisectable, having a commit that changes
MSI/MSIX code but describes it as "fix vhost-user-blk compilation" is
rather confusing.
Revert the offending commit to properly apply both patches separately.

Reported-by: Peter Xu <peterx@redhat.com>
Fixes: a56de056
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20190212140621.17009-2-philmd@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>