RFR: 8336463: Parallel: Add PSOldGen::expand_and_allocate

[Albert Mingkun Yang]

Simple adding an API to old-gen to support calls by VM thread in safepoint.

Test: tier1-3

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Commit messages:
 - pgc-expand

Changes: https://git.openjdk.org/jdk/pull/20189/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20189&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8336463
  Stats: 32 lines in 5 files changed: 22 ins; 6 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/20189.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20189/head:pull/20189

PR: https://git.openjdk.org/jdk/pull/20189