[lworld] RFR: 8326990: [lworld] make value classes a preview feature [v3]

[Vicente Romero]

> Javac changes to make value classes a preview feature,
> 
> TIA

Vicente Romero has updated the pull request incrementally with one additional commit since the last revision:

  minor changes to tests

-------------

Changes:
  - all: https://git.openjdk.org/valhalla/pull/1037/files
  - new: https://git.openjdk.org/valhalla/pull/1037/files/630dc629..4acb4f1d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=valhalla&pr=1037&range=02
 - incr: https://webrevs.openjdk.org/?repo=valhalla&pr=1037&range=01-02

  Stats: 4 lines in 4 files changed: 1 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/valhalla/pull/1037.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1037/head:pull/1037

PR: https://git.openjdk.org/valhalla/pull/1037