This gives moderate speed improvements when hashing small keys.
The crc/adler/fnv inlining did not provide enough speed up to warrant
the change.
OLD:
wyhash
small keys: 2277 MiB/s [c14617a1e3800000]
siphash(1,3)
small keys: 937 MiB/s [b2919222ed400000]
siphash(2,4)
small keys: 722 MiB/s [3c3d974cc2800000]
fnv1a
small keys: 1580 MiB/s [70155e1cb7000000]
adler32
small keys: 1898 MiB/s [00013883ef800000]
crc32-slicing-by-8
small keys: 2323 MiB/s [0035bf3dcac00000]
crc32-half-byte-lookup
small keys: 218 MiB/s [0035bf3dcac00000]
NEW:
wyhash
small keys: 2775 MiB/s [c14617a1e3800000]
siphash(1,3)
small keys: 1086 MiB/s [b2919222ed400000]
siphash(2,4)
small keys: 789 MiB/s [3c3d974cc2800000]
fnv1a
small keys: 1604 MiB/s [70155e1cb7000000]
adler32
small keys: 1856 MiB/s [00013883ef800000]
crc32-slicing-by-8
small keys: 2336 MiB/s [0035bf3dcac00000]
crc32-half-byte-lookup
small keys: 218 MiB/s [0035bf3dcac00000]
