TM :: Transaction locking

We implement mutex here using lock sets; as the number of semaphores may be limited (e.g. sysv) and number of synchronized elements high, we partition the synced SER elements and share semaphores in each of the partitions; we try to use as many semaphores as OS gives us for finest granularity.

we allocate the locks according to the following plans:

-1) transaction timer lists have each a semaphore in a semaphore set -2) retransmission timer lists have each a semaphore in a semaphore set -3) we allocate a semaphore set for hash_entries and try to use as many semaphores in it as OS allows; we partition the hash_entries by available semaphores which are shared in each partition -4) cells get always the same semaphore as its hash entry in which they live