[lworld] RFR: 8288131: [lworld] Implement javac flag -XDenablePrimitiveClasses [v3]

[Vicente Romero]

> Primitive classes support should be opted in using a compiler option

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

  fixing jdk tests

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

Changes:
  - all: https://git.openjdk.org/valhalla/pull/758/files
  - new: https://git.openjdk.org/valhalla/pull/758/files/f5827c6b..e532288d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=valhalla&pr=758&range=02
 - incr: https://webrevs.openjdk.org/?repo=valhalla&pr=758&range=01-02

  Stats: 31 lines in 26 files changed: 23 ins; 0 del; 8 mod
  Patch: https://git.openjdk.org/valhalla/pull/758.diff
  Fetch: git fetch https://git.openjdk.org/valhalla pull/758/head:pull/758

PR: https://git.openjdk.org/valhalla/pull/758