Use Spin locks on Tile

On Tile, replace pthread_mutex_locks with queued spin locks (ticket
locks) for dataplane processing code. This is safe when running on
dataplane cores with one thread per core. The condition variables are
no-ops when the thread is spinning anyway.

For control plane threads, unix-manager, stats-logs, thread startup,
use pthread_mutex_locks. For these locks replaced SCMutex with SCControlMutex
and SCCond with SCControlCond.