RFR: CODETOOLS-7902983: jcstress: Improve performance for tests with many results [v3]

[Aleksey Shipilev]

> As reported here:
>   https://mail.openjdk.java.net/pipermail/jcstress-dev/2021-June/000702.html
> 
> Cache the grading, optimize HTML table generation a little.

Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains two commits:

 - Use TreeMap to poll results in HTML report
 - CODETOOLS-7902983: jcstress: Improve performance for tests with many results

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Changes: https://git.openjdk.java.net/jcstress/pull/86/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jcstress&pr=86&range=02
  Stats: 35 lines in 4 files changed: 9 ins; 3 del; 23 mod
  Patch: https://git.openjdk.java.net/jcstress/pull/86.diff
  Fetch: git fetch https://git.openjdk.java.net/jcstress pull/86/head:pull/86

PR: https://git.openjdk.java.net/jcstress/pull/86