Pass calibrated TSC frequency to vmm(4) guests. On machines where TSC

Pass calibrated TSC frequency to vmm(4) guests.  On machines where TSC
cannot be calculated from the CPUID register, because the CPU does not
support it, but can be calibrated from another timer, the vmm(4) guest
doesn't have a chance to read or calibrate its own TSC frequency since
it has no access to a precise enough time counter.  In that case, fake
the existence of the register and supply our calibrated TSC frequency.
mlarkin@ tells me this also greatly helps Linux guests.

ok mlarkin@