RFR: 8259800: timeout in tck test testForkJoin(ForkJoinPool8Test)

[Doug Lea]

This addresses interactions between parallelism-0 and new shutdown support in https://bugs.openjdk.java.net/browse/JDK-8259800

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Commit messages:
 - JDK-8259800

Changes: https://git.openjdk.java.net/jdk/pull/2661/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2661&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8259800
  Stats: 347 lines in 2 files changed: 175 ins; 106 del; 66 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2661.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2661/head:pull/2661

PR: https://git.openjdk.java.net/jdk/pull/2661