cpu_start_mp(). This is after we have read the cpuid registers to
calculate the hyperthreading_cpus value for the sysctl that enables or
disables hyperthread cores. Change mp_topology() to use that information
rather than trying to do it itself.
This solves the problem of ULE being incorrectly told that dual core
Athlon64 X2 or Operton cpus are hyperthreading cores. At the very least,
we now have a single piece of code to identify hyperthreading.
Obtained from: jhb
Approved by: re (kensmith)
b7778ae08f