[lworld] RFR: 8327080: [lworld] Update Valhalla micros to JEP 401

[Roger Riggs]

A bulk update to change "primitive class" to "value class, remove .ref and replace .default with no-arg constructor. 
Plus other changes to get the benchmarks to compile.

No assertions are made beyond compilation.  The generated benchmarks.jar is well formed and can list the benchmarks.

The makefile rule build-microbenchmark is re-enabled for the `test` target.

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Commit messages:
 - 8327080: [lworld] Update Valhalla micros to JEP 401

Changes: https://git.openjdk.org/valhalla/pull/1028/files
 Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1028&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8327080
  Stats: 707 lines in 116 files changed: 75 ins; 2 del; 630 mod
  Patch: https://git.openjdk.org/valhalla/pull/1028.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1028/head:pull/1028

PR: https://git.openjdk.org/valhalla/pull/1028