RFR: 8344259: Annotate Float16 with jdk.internal.ValueBased

[Joe Darcy]

On Fri, 15 Nov 2024 00:25:20 GMT, Paul Sandoz <psandoz at openjdk.org> wrote:

> Annotate `Float16` with `jdk.internal.ValueBased`. This requires we export the package `jdk.internal` in module `java.base` to module` jdk.incubator.vector`.
> 
> Doing so enables the compiler and runtime to report warnings about improper attempts to synchronize on instances of `Float16`, as described in [JEP 390](https://openjdk.org/jeps/390).

Looks fine; please manually verify the expected javac warnings are given for misuse of Float16 in non-value ways.

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Marked as reviewed by darcy (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/22128#pullrequestreview-2437474278