[jdk15u-dev] RFR: 8260704: ParallelGC: oldgen expansion needs release-store for _end

[Olga Mikhaltsova]

I'd like to backport JDK-8260704 to jdk15u for parity with jdk11u.
The original patch applied manually due to the slight context changes.
All regular tests passed.

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Commit messages:
 - Backport afd5eefdae388a53a0d6bffc2cf94b878ac1881e

Changes: https://git.openjdk.java.net/jdk15u-dev/pull/100/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk15u-dev&pr=100&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8260704
  Stats: 11 lines in 2 files changed: 4 ins; 1 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk15u-dev/pull/100.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk15u-dev pull/100/head:pull/100

PR: https://git.openjdk.java.net/jdk15u-dev/pull/100