C99 translation of Bob Jenkins' SpookyHash.
This version of SpookyHash is translated from Bob Jenkin's original code (V2). For performance metrics and testing, please see Reini Urban's smhasher fork.
The code is meant to be platform agnostic. However, 64 bit operations are
used heavily in the hashes, including rotate left which is not optimized
for any specific platform. Unaligned reads are assumed cheap and allowed by
default. Also note, the hashes will produce different values depending on
machine endianness.