RFR: 8259851: Using boolean type for tasks in SubTasksDone

Mon Jan 18 14:23:57 UTC 2021

Changing `uint` to `bool` in `SubTasksDone`, since atomic operations on `bool` are well supported.

Tested: hotspot_gc

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Commit messages:
 - bool

Changes: https://git.openjdk.java.net/jdk/pull/2131/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2131&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8259851
  Stats: 13 lines in 2 files changed: 0 ins; 6 del; 7 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2131.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2131/head:pull/2131

PR: https://git.openjdk.java.net/jdk/pull/2131