... which is needed for app-emulation/libvirt-0.9.10-r4. Do I have to change my host declarations or is this an re-incarnation of bug 369163 and 343951?
Its not needed for libvirt. You didn't read the ewarn: ewarn "The depreciated '/usr/bin/kvm' symlink is no longer installed" ewarn "You should use '/usr/bin/qemu-kvm', you may need to edit" ewarn "your libvirt configs or other wrappers for qemu-kvm" The correct wrapper to use is "qemu-kvm". "kvm" is extremely old from app-emulation/kvm and we had been including a symlink to "qemu-kvm" as a convince to people. But in the future "kvm" and "qemu" will be used by the upstream packages for something.