[crac] RFR: 8346796: [CRaC] Initialize clock before restore on Mac

[Timofei Pushkin]

This should fix `jdk/crac/recursiveCheckpoint/Test.java` failures on MacOS.

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Commit messages:
 - Initialize clock before restore

Changes: https://git.openjdk.org/crac/pull/169/files
  Webrev: https://webrevs.openjdk.org/?repo=crac&pr=169&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8346796
  Stats: 5 lines in 1 file changed: 5 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/crac/pull/169.diff
  Fetch: git fetch https://git.openjdk.org/crac.git pull/169/head:pull/169

PR: https://git.openjdk.org/crac/pull/169