Split up fticks.c in order not to have to drag in too much of
radsecproxy in order to just hash a MAC.

Almost closes RADSECPROXY-16.

Comment on VendorKeyHashed, from source:
We are hashing the first nine octets too for easier correlation
between vendor-key-hashed and fully-key-hashed log records.  This
opens up for a known plaintext attack on the key but the consequences
of that is considered outweighed by the convenience gained.

We produced 62 octets rather than 64.

(format_hash): Don't write past OUT_LEN.  Duh!

Also, log empty string if no Calling-Station-Id attribute is found.