RFR: Merge jdk8u:master

[Andrew John Hughes]

Merge jdk8u402-b03

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-b03
 - 8176509: Use pandoc for converting build readme to html
 - 8317291: Missing null check for nmethod::is_native_method()

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

Changes: https://git.openjdk.org/shenandoah-jdk8u/pull/62/files
  Stats: 5007 lines in 17 files changed: 2140 ins; 2854 del; 13 mod
  Patch: https://git.openjdk.org/shenandoah-jdk8u/pull/62.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah-jdk8u.git pull/62/head:pull/62

PR: https://git.openjdk.org/shenandoah-jdk8u/pull/62