+/**
+ * tdb1_incompatible_hash - better (Jenkins) hash for tdb1
+ *
+ * This is better than the default hash for tdb1; but older versions of the
+ * tdb library (prior to version 1.2.6) won't be able to open them.
+ *
+ * It only makes sense to specify this (using tdb_attribute_hash) when
+ * creating (with O_CREAT) an old tdb version using TDB_VERSION1. It's
+ * equivalent to the TDB_INCOMPATIBLE_HASH flag for tdb1.
+ */
+uint64_t tdb1_incompatible_hash(const void *, size_t, uint64_t, void *);
+