Even though qemu-kvm binaries can be used in TCG mode, libvirt would
only detect them if /dev/kvm was available. Thus, one would need to make
a /usr/bin/qemu symlink to be able to use TCG mode with qemu-kvm in an
environment without KVM support.

And even though QEMU is able to make use of KVM, libvirt would not
advertise KVM support unless there was a qemu-kvm symlink available.

This patch fixes both issues.