RFR: 8355971: Build warnings after the changes for JDK-8354996

[Aleksey Shipilev]

On Wed, 30 Apr 2025 17:32:34 GMT, Chen Liang <liach at openjdk.org> wrote:

> There were a few warnings related to illegal native access in HelloClasslist after adding some of the downcall infrastructure. Did a clean build and there were no warning associated with the 
> 
> Compiling up to 2 files for CLASSLIST_JAR
> Creating support/classlist.jar
> 
> steps.

Just caught it in my builds. Fix makes sense.

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Marked as reviewed by shade (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/24970#pullrequestreview-2808113806