The UNIX socket FDs were we passing to QEMU inherited a label based on
libvirtd's context. QEMU is thus denied ability to access the UNIX
socket. We need to use the security manager to change our current
context temporarily when creating the UNIX socket FD.
Reviewed-by: NLaine Stump <laine@laine.org>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>