Integrated: Merge lworld

[Vicente Romero]

Merge branch 'lworld' into lw5_merge_lworld

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Commit messages:
 - Merge branch 'lworld' into lw5_merge_lworld
 - 8314181: [lw5] the check for illegal circularity should only be done if value classes are available
 - 8314165: [lw5] check for illegal circularity at class loading time
 - Merge lworld
 - [lw5] regression test cleanup, relocation
 - [lw5] fixing bugs on experimental code to generate Q-descriptors, plus code refactoring
 - [lw5] experiment: reusing primitive class tests to generate Q descriptors
 - Merge lworld
 - experiment: generate Q descriptors for lw5 code
 - 8313080: [lw5] javac parser is not accepting some array types with nullness markers
 - ... and 13 more: https://git.openjdk.org/valhalla/compare/9ceb30ba...875ef365

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

Changes: https://git.openjdk.org/valhalla/pull/912/files
  Stats: 6239 lines in 239 files changed: 3507 ins; 1753 del; 979 mod
  Patch: https://git.openjdk.org/valhalla/pull/912.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/912/head:pull/912

PR: https://git.openjdk.org/valhalla/pull/912