[Sheepdog] add some candy helpers

[MORITA Kazutaka]

At Thu, 17 Nov 2011 17:50:00 +0800,
Liu Yuan wrote:
> 
> These candy helpers are spin-offs from the development "Farm". I don't know
> when Farm will be released, so I think it would be useful for other dev to include
> these helerps in early. Most are taken from Linux kernel, git.
> 
> V3 changes:
>  - move util.c in lib/, then logger and collie can call these funcs.
> 
> v2 changes:
>  - drop simple slab allocator
>  - drop hash_long(), use fnv_64a_buf() as kazum suggested.
>  - add xpread, xpwrite helpers.

Applied, thanks!

Kazutaka