RFR (XS) 8181450: assert in BasicHashtable::verify_table

[Kim Barrett]

> On Jun 15, 2017, at 8:21 PM, coleen.phillimore at oracle.com wrote:
> 
> Summary: remove assert as it has small probability of happening and add some logging
> 
> Tested new logging with -Xlog:hashtables with failed tests.   See bug report for more information.
> 
> open webrev at http://cr.openjdk.java.net/~coleenp/8181450.01/webrev
> bug link https://bugs.openjdk.java.net/browse/JDK-8181450
> 
> Thanks,
> Coleen

Looks good.