RFR (S) 8182554: Code for os::random() assumes long is 32 bits

[Kim Barrett]

> On Jun 28, 2017, at 3:54 PM, coleen.phillimore at oracle.com wrote:
> 
> 
> Stefan had comments offline so here's another version to review that removes more (int) casts and reverts the return type of althashing object_hash(), and fixed the comment in synchronizer.cpp.
> 
> open webrev at http://cr.openjdk.java.net/~coleenp/8182554.02/webrev
> 
> Let me know if this looks good.
> thanks,
> Coleen

Looks good.