[libvirt] 0.6.2: git mirror tagged, too

[Jim Meyering]

Mark McLoughlin mentioned that the LIBVIRT_0_6_2 tag was not automatically
mirrored into the git tree, so I've added it.  I also added a signed
tag on the same change set.  Among other things, that makes it so that
"git describe" now generates sensible output for recent changes.

But adding all the rest would be nice, too, so I did it with this

    for tag in $(git tag -l 'LIBVIRT_0_[0-5]*'); do
      v=$(echo $tag|sed 's/LIBVIRT_/v/;s/_/./g')
      git tag -s -m $v $v $tag
    done

and pushed those tags.