core: make object cache LIFO
core: make object cache LIFO

was originally LIFO and I broke that when switching to the queue.h code.
This is friendlier for cache.

memcached/memcached,dormando/memcached,memcached/memcached,memcached/memcached,dormando/memcached,memcached/memcached,dormando/memcached,memcached/memcached,dormando/memcached,dormando/memcached