RFR: 8274349: ForkJoinPool.commonPool() does not work with 1 CPU

[David Holmes]

A regression introduced in Java 17 will give the default  FJ pool a parallelism of zero in a uniprocessor environment. The fix restores this to a value of 1. See bug report for details.

Testing:
 - new regression test
 - tiers 1-3

Thanks,
David

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Commit messages:
 - 8274349: ForkJoinPool.commonPool() does not work with 1 CPU

Changes: https://git.openjdk.java.net/jdk/pull/5784/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5784&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8274349
  Stats: 47 lines in 2 files changed: 46 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5784.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5784/head:pull/5784

PR: https://git.openjdk.java.net/jdk/pull/5784