RFR: 8291970: Add TableStatistics get function to ResourceHashtable

[Ioi Lam]

On Fri, 5 Aug 2022 14:47:39 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

> Add a statistics_calculate function to ResourceHashtable so that we can use it for printing.  Also add a test.
> Tested with tier1 on Oracle platforms (with and without product build).

Looks good.

I think the test can be simplified by using `ResourceHashtable<int, TestValue>` so you don't need to explicitly delete the values.

-------------

Marked as reviewed by iklam (Reviewer).

PR: https://git.openjdk.org/jdk/pull/9775