RFR 8214821: Remove ConcurrentHashTable::get_copy

[Kim Barrett]

> On Jan 23, 2019, at 1:49 PM, Gerard Ziemski <gerard.ziemski at oracle.com> wrote:
> 
> Hi all,
> 
> Please review this simple fix that removes “ConcurrentHashTable::get_copy” API, whose only client was a single gtest. Doing so allows us to remove CONFIG::notfound()
> 
> That gtest replaces the usage of “get_copy” API with a local “cht_get_copy” method, which itself is implemented using "ConcurrentHashTable::get” API
> 
> I also took this opportunity to clean up a few method names in the test a bit.
> 
> References:
> 
> https://bugs.openjdk.java.net/browse/JDK-8214821
> http://cr.openjdk.java.net/~gziemski/8214821_rev1
> 
> Passes gtest locally on Mac and passes Mach5 hs-tier1,2,3,4,5,6
> 
> 
> Cheers

Looks good.