BUG/MEDIUM: cpu-topo: Enforce thread-hard-limit on policy

BUG/MEDIUM: cpu-topo: Enforce thread-hard-limit on policy

When a policy is set, and the number of threads is calculated
dynamically, make sure we enforce thread-hard-limit, and do not create
thread groups based on how many thread we would have created without
the limit.
This should be backported to 3.3 and 3.2. The patch won't apply cleanly
there, because the code has changed since then, but it should be very
similar, only we'll have to check "cpu_count" there, where in 3.4 we
check "thr_count".