Recently (or not so recently) QEMU added the kvm32 and kvm64
architectures, representing a least common denominator of all
hosts that can run KVM.  Add them to the machine map.

Also, some features that TCG supports were added to qemu64.
Add them to the cpu_map.xml whenever KVM is guaranteed to support
those.  We still have to leave some out, because they would not
be available to guests running on older hosts.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>