[Commited] Extend BFD hash size table

[Doug Evans]

Nick Clifton writes:
 > > if we had a better hashing function, we wouldn't need
 > > prime table sizes and could just use power-of-2 tables and replace all those
 > > modulo operations with bitwise ANDs.]
 > 
 > I have always thought that using prime numbers as the hash table size 
 > was necessary in order to get an efficient use of all the buckets.  Of 
 > course this may just be an urban myth, I do not know of any actual 
 > theoretical work to back this up.

Knuth Volume 3, 6.4 Hashing  ?