Make the size for the syn cache hash array tunable. As we are

Make the size for the syn cache hash array tunable.  As we are
swapping between two syn caches for random reseeding anyway, this
feature can be added easily.  When the cache is empty, there is an
opportunity to change the hash size.  This allows an admin under
SYN flood attack to defend his machine.
Suggested by claudio@; OK jung@ claudio@ jmc@