RFR: 8300652: Parallel: Refactor oop marking stack in Full GC

[Albert Mingkun Yang]

Simple rename of the oop marking stack.

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Commit messages:
 - pgc-oop-stack

Changes: https://git.openjdk.org/jdk/pull/12095/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12095&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8300652
  Stats: 10 lines in 3 files changed: 0 ins; 0 del; 10 mod
  Patch: https://git.openjdk.org/jdk/pull/12095.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12095/head:pull/12095

PR: https://git.openjdk.org/jdk/pull/12095