RFR: 7903491: jcstress: Run time budget [v8]

[Aleksey Shipilev]

> Real-world testing with jcstress frequently runs into capacity problems. There are usually tons of tests in the suite, and there are many JVM options that default runner is traversing by default. This often comes as a nasty surprise for the testers, when the full run starts taking months.
> 
> There are "run profiles", selected with `-m`, which are supposed to help here, but they are not that handy to use, and are following the hand-selected hard-coded settings in the harness options.
> 
> Instead, we can do a better thing: introduce the "run time budget" option, where a user can say "I have around X hours to run these tests, figure out the best test configuration to fit this time".
> 
> This would make jcstress naturally usable in nightly runs, where we can ask for 1 hour run, weekly runs, where we can ask for 8 hour run, monthly runs, where we can ask for 24 hours run.

Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:

  Policy adjustments

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Changes:
  - all: https://git.openjdk.org/jcstress/pull/139/files
  - new: https://git.openjdk.org/jcstress/pull/139/files/694c89e8..bc111c38

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jcstress&pr=139&range=07
 - incr: https://webrevs.openjdk.org/?repo=jcstress&pr=139&range=06-07

  Stats: 7 lines in 1 file changed: 4 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jcstress/pull/139.diff
  Fetch: git fetch https://git.openjdk.org/jcstress.git pull/139/head:pull/139

PR: https://git.openjdk.org/jcstress/pull/139