This is a reland of commit 5592bad9

- Disable timeout signal handler with --fuzzing
- Properly initialize sigaction object

Original change's description:
> [d8] Dump stack trace on d8 tests timeouts on posix systems
>
> - Add a SIGTERM handler in d8 that dupms the stack trace
> - Send SIGTERM before SIGKILL in the test runner
>
> Bug: v8:13115
> Change-Id: I75285f33caabab61ff6ae83c1fbc6faf45cf595a
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3791906
> Reviewed-by: Michael Achenbach <machenbach@chromium.org>
> Reviewed-by: Igor Sheludko <ishell@chromium.org>
> Commit-Queue: Camillo Bruni <cbruni@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#82173}

Bug: v8:13115
Change-Id: I115cc3f671ebe11ba204e75a6fc358ca3477e950
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3820221Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82361}