Fixes Akaros ticksperns

Also prints out the Avg vs pre-computed times.  It's a little disturbing
if these differ.
Fixes nsec() on linux

Was treating a second as a 2^30 nsec, instead of 10^9.
Populates and pins samples[]

So we don't PF during the benchmark.

Memsetting the threads array isn't strictly necessary, since they are
faulted in before we release the hounds, but it will do the PFs as an
SCP.