[crac] RFR: 8347257: [CRaC] Checkpoint call may sometimes hang

[Timofei Pushkin]

When checkpointing, "Common-Cleaner" thread sometimes runs into an infinite loop. This change fixes the infinite loop.

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Commit messages:
 - Fix line endings
 - Checkpoint call may sometimes hang

Changes: https://git.openjdk.org/crac/pull/175/files
  Webrev: https://webrevs.openjdk.org/?repo=crac&pr=175&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8347257
  Stats: 140 lines in 3 files changed: 116 ins; 20 del; 4 mod
  Patch: https://git.openjdk.org/crac/pull/175.diff
  Fetch: git fetch https://git.openjdk.org/crac.git pull/175/head:pull/175

PR: https://git.openjdk.org/crac/pull/175