Remove judy and use glib hash tables.

There is no significant advantage to use Judy arrays over glib
HashTables to store hashes in fuzzy storage. Therefore, drop support of
Judy completely. Also rename `use_judy` parameter to `strict_hash`
indicating that hashes are matched strictly (not a fuzzy match but a hash
lookup).
Move xxhash to contrib.
Rework bloom hash library to use XXHash.