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
 - Merge lworld
 - 8314913: [lw5] null restrictions can only be applied to value classes
 - 8314899: [lw5] rename j.l.NonAtomic to j.l.LooselyConsistentValue
 - 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
 - ... and 17 more: https://git.openjdk.org/valhalla/compare/3b4cc5fd...b182f4f2

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

Changes: https://git.openjdk.org/valhalla/pull/923/files
  Stats: 6286 lines in 239 files changed: 3553 ins; 1757 del; 976 mod
  Patch: https://git.openjdk.org/valhalla/pull/923.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/923/head:pull/923

PR: https://git.openjdk.org/valhalla/pull/923