[ovs-dev] classifier mutex

[Ben Pfaff]

The classifier has an internal mutex, but in ofproto that mutex is
redundant with the external ofproto_mutex.  If the classifier mutex were
removed, to be replaced by documentation that certain routines need
mutual exclusion, then possibly the reduced locking could yield a
performance improvement.

However, I don't think any of the functions that take the lock are on
fast paths anyway, so this is just a thought.