RFR: 7904034: jcstress: Run with global int/C1/C2 modes even with split compilation [v2]

[Aleksey Shipilev]

> WIP.
> 
> [JDK-8351997](https://bugs.openjdk.org/browse/JDK-8351997) shows there is a gap in current configuration coverage with jcstress. When split compilation is enabled, harness asks to int/C1/C2 each actor method separately. Unfortunately, there are cases in Hotspot where the barrier scheme depends on whether C2 is globally enabled. [JDK-8351997](https://bugs.openjdk.org/browse/JDK-8351997) would fail split int/C1 test with C2 globally disabled.
> 
> Therefore, harness should run with global int/C1/C2 modes even with split compilation. This complicates testing matrix quite a bit, but it should capture bugs like [JDK-8351997](https://bugs.openjdk.org/browse/JDK-8351997) more reliably.

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

  Cleanups

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

Changes:
  - all: https://git.openjdk.org/jcstress/pull/168/files
  - new: https://git.openjdk.org/jcstress/pull/168/files/4c2fb25a..16ad3c03

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jcstress&pr=168&range=01
 - incr: https://webrevs.openjdk.org/?repo=jcstress&pr=168&range=00-01

  Stats: 46 lines in 2 files changed: 17 ins; 2 del; 27 mod
  Patch: https://git.openjdk.org/jcstress/pull/168.diff
  Fetch: git fetch https://git.openjdk.org/jcstress.git pull/168/head:pull/168

PR: https://git.openjdk.org/jcstress/pull/168