qemu: Fix access to auto-generated socket paths
    
    We are automatically generating some socket paths for domains, but all
    those paths end up in a directory that's the same for multiple domains.
    The problem is that multiple domains can each run with different
    seclabels (users, selinux contexts, etc.).  The idea here is to create a
    per-domain directory labelled in a way that each domain can access its
    own unix sockets.
    
    Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1146886
    
    Signed-off-by: Martin Kletzander <mkletzan@redhat.com>