[BSA-052] Security Update for libvirt

Guido Günther uploaded new packages for libvirt which fixed the
following security problems:

CVE-2011-2511
Integer overflow in VirDomainGetVcpus

CVE-2011-1486
Non thread safe error reporting

For the squeeze-backports distribution the problems have been fixed in
version 0.9.2-7~bpo60+1.

For the lenny-backports distribution the problems have been fixed in
version 0.8.3-5+squeeze2~bpo50+2.

For lenny-backports only:

If you don't use pinning (see [1]) you have to update the package
manually via "apt-get -t lenny-backports install <packagelist>" with
the packagelist of your installed packages affected by this update.
[1] <http://backports.debian.org/Instructions&gt;

We recommend to pin (in /etc/apt/preferences) the backports repository to
200 so that new versions of installed backports will be installed
automatically.

Package: *
Pin: release a=lenny-backports
Pin-Priority: 200