[lworld] RFR: 8288131: [lworld] Implement javac flag -XDenablePrimitiveClasses [v5]

[Vicente Romero]

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

Vicente Romero has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 16 commits:

 - Merge branch 'lworld' into JDK-8288131
 - removing the latest changes to VarHandles tests
 - fixing varhandle tests
 - fixing benchmark tests
 - fixing jdk tests
 - fixing additional HS tests
 - removing whitespace
 - Merge branch 'lworld' into JDK-8288131
 - removing whitespace
 - fixing more hotspot tests
 - ... and 6 more: https://git.openjdk.org/valhalla/compare/56dfc296...e42cd658

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Changes: https://git.openjdk.org/valhalla/pull/758/files
 Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=758&range=04
  Stats: 396 lines in 268 files changed: 166 ins; 43 del; 187 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