[jdk23u] RFR: 8341722: Fix some warnings as errors when building on Linux with toolchain clang

[Christoph Langer]

On Mon, 4 Nov 2024 15:28:00 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

> Backport of 8341722, changes of Lib.gmk are not in 23u so I omit those; otherwise applied clean.

Marked as reviewed by clanger (Reviewer).

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PR Review: https://git.openjdk.org/jdk23u/pull/213#pullrequestreview-2413453830