RFR 8231075: Prototype HashMap implementations using inline classes

[Roger Riggs]

To evaluate the techniques and performance of using inline classes for 
HashMap
a couple of implementations are prototyped with JMH tests.  More work is 
needed
to evaluate the performance and improve the algorthms.

Webrev:
    http://cr.openjdk.java.net/~rriggs/webrev-xmap-perf-8231075-1/

Thanks, Roger