Collisions in multihash_cid cause problems with wildcard flush

I've had problems with wildcard flushes not working satisfactory. I've tracked the source of the problem to the implementation of memcache_multihash_cid.

The problem is that results are cached in the static array $hashes using only $cid as key. This causes incorrect behavior when subsequent calls are made with identical $cid but different $table. The second request will receive all the hashes of the first request which is wrong.

I've written a patch for 6-1 that fixes this and solves my problems with wildcard flushes. The code in 7-1 is similar and also in need of similar patching.