Summary: AltHashing used jint the way of juint in bit shifting which could lead loss of precision. Fix  by change _seed defined as juint.
Reviewed-by: coleenp, ccheung
Contributed-by: yumin.qi@oracle.com

Summary: Use an alternate version of hashing algorithm for symbol string tables and after a certain bucket size to improve performance
Reviewed-by: pbk, kamg, dlong, kvn, fparain