RFR: 8308594: Use atomic bitset function for PackageEntry::_defined_by_cds_in_class_path

[Calvin Cheung]

Please review this simple fix for replacing the implementation in `PackageEntry::set_defined_by_cds_in_class_path()` with `Atomic::fetch_then_or()`.

Passed tier1 testing.

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Commit messages:
 - 8308594: Use atomic bitset function for PackageEntry::_defined_by_cds_in_class_path

Changes: https://git.openjdk.org/jdk/pull/14164/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14164&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8308594
  Stats: 6 lines in 1 file changed: 0 ins; 5 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/14164.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14164/head:pull/14164

PR: https://git.openjdk.org/jdk/pull/14164