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

[Mandy Chung]

On Thu, 29 Feb 2024 22:44:12 GMT, Roger Riggs <rriggs at openjdk.org> wrote:

> 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.

LGTM.   This patch allows the microbenchmarks target to be enabled again.   As Sergey commented offline, these microbenchmarks should be completely rewritten.

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Marked as reviewed by mchung (Committer).

PR Review: https://git.openjdk.org/valhalla/pull/1028#pullrequestreview-1918079942