[lworld] RFR: 8327636: [lworld] Make primitive wrappers be value class if preview feature is enabled

[Mandy Chung]

As specified in JEP 401, when preview features are enabled, the following standard library classes are considered to be value classes:

    java.lang.Byte
    java.lang.Short
    java.lang.Integer
    java.lang.Long
    java.lang.Float
    java.lang.Double
    java.lang.Boolean
    java.lang.Character
    java.util.Optional
    java.lang.Number
    java.lang.Record


These value classes are loaded only if --enable-preview is set.    All valhalla tests should have preview enabled to ensure testing with the proper set of library classes.

Testing: Run `jdk_valhalla` and `hotspot_valhalla_runtime` with  `-Xint` with and without `--enable-preview`.  The result is pretty good.  [JDK-8327637](https://bugs.openjdk.org/browse/JDK-8327637) and [JDK-8327639](https://bugs.openjdk.org/browse/JDK-8327639) need further investigation.

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Commit messages:
 - 8327636: [lworld] Make primitive wrappers be value class if preview feature is enabled

Changes: https://git.openjdk.org/valhalla/pull/1040/files
 Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1040&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8327636
  Stats: 23 lines in 3 files changed: 17 ins; 4 del; 2 mod
  Patch: https://git.openjdk.org/valhalla/pull/1040.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1040/head:pull/1040

PR: https://git.openjdk.org/valhalla/pull/1040