[8u] RFR(XS) 8231494: fix a typo in hash functions

[Liu, Xin]

Hi, reviewer,

Could you review this trivial change?  I think it’s a typo and get better hash function.
JBS: https://bugs.openjdk.java.net/browse/JDK-8231494
Webrev: https://cr.openjdk.java.net/~xliu/8231494/webrev/

I didn’t backport JDK-8055283 because it’s not necessary.

Thanks,
--lx