hash: update jhash function with the latest available

hash: update jhash function with the latest available

Jenkins hash function was developed originally in 1996,
and was integrated in first versions of DPDK.
The function has been improved in 2006,
achieving up to 35% better performance, compared to the original one.

This patch integrates that code into the rte_jhash library.
It also updates the precalculated hash values in the unit test,
as the code now returns different values (expected).

A final note has been added in release notes for stating
the changes made.

Signed-off-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>