RFR: 8299956: [BACKOUT] 8297487: G1 Remark: no need to keep alive oop constants of nmethods on stack

[Tobias Hartmann]

Clean backout after we observed various crashes with different tests after the integration of [JDK-8297487](https://bugs.openjdk.org/browse/JDK-8297487).

Thanks,
Tobias

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Commit messages:
 - Revert "8297487: G1 Remark: no need to keep alive oop constants of nmethods on stack"

Changes: https://git.openjdk.org/jdk/pull/11941/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11941&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8299956
  Stats: 16 lines in 2 files changed: 13 ins; 1 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/11941.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11941/head:pull/11941

PR: https://git.openjdk.org/jdk/pull/11941