RFR: 8366225: Linux Alpine (fast)debug build fails after JDK-8365909

[Matthias Baesken]

On Wed, 27 Aug 2025 11:33:53 GMT, Manuel Hässig <mhaessig at openjdk.org> wrote:

> The integration of #26882 broke debug builds on Alpine Linux (and probably other distributions using musl libc), because the typedef `sigevent_t`does not exist in musl libc. This PR fixes this by using `struct sigevent` as the type.
> 
> Testing:
>  - [ ] Github Actions
>  - [ ] tier1,tier2 Linux aarch64 and x64 fastdebug
>  - [x] `make test TEST=compiler/arguments/TestCompileTaskTimeout.java` in Alpine Linux docker container 
>  - [ ] tier1,tier2 on Alpine Linux fastdebug

This fixes the Linux Alpine fastdebug build.

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Marked as reviewed by mbaesken (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/26956#pullrequestreview-3159607284