RFR: Merge jdk8u:master

[Andrew John Hughes]

Merge jdk8u402-b02

GHA builds will not work until [JDK-8293107](https://bugs.openjdk.org/browse/JDK-8293107) is merged in 8u462-b01

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Commit messages:
 - Merge jdk8u402-b02
 - 8305329: [8u] Unify test libraries into single test library - step 1
 - 8319405: [s390] [jdk8] Increase javac default stack size for s390x zero

The merge commit only contains trivial merges, so no merge-specific webrevs have been generated.

Changes: https://git.openjdk.org/shenandoah-jdk8u/pull/61/files
  Stats: 1934 lines in 612 files changed: 15 ins; 1449 del; 470 mod
  Patch: https://git.openjdk.org/shenandoah-jdk8u/pull/61.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah-jdk8u.git pull/61/head:pull/61

PR: https://git.openjdk.org/shenandoah-jdk8u/pull/61