RFR: 8329884: Serial: Fix build failure due to ‘Copy’ has not been declared

[Jie Fu]

Please review the trivial change which fixes the build failure of serial gc (e.g., build the minimal-release).
Thanks.

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Commit messages:
 - 8329884: Serial: Fix build failure due to ‘Copy’ has not been declared

Changes: https://git.openjdk.org/jdk/pull/18682/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18682&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8329884
  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/18682.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18682/head:pull/18682

PR: https://git.openjdk.org/jdk/pull/18682