Revert "Restore default behaviour of signal handling"

This reverts commit 46b18e26.

Reason for revert: Sheriff. Broke android-asna.
crbug.com/1195009

Original change's description:
> Restore default behaviour of signal handling
>
> Arm's new security features (PAC, BTI, MTE) often crash the process with
> an appropriate signal in the event of a security problem. When writing
> tests to verify this behaviour, it is crucial to ensure that tests exit
> with exit codes that reflect the signal.
>
> For Linux this patch removes the explicit termination of the process via
> exit(1) and re-raises the signal to invoke the default signal handler
> and ensure proper (default) handling of the signal, including exiting
> with correct exit code.
>
> On other posix compliant operating systems the signal handler still
> terminates the process with an exit code of 1.
>
> Bug: 1137393, 1145581
> Change-Id: I0260f8bbccafe38860cef2dbc696701b57fc155c
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2777558


> Reviewed-by: Daniel Cheng <dcheng@chromium.org>
> Reviewed-by: Chris Palmer <palmer@chromium.org>
> Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
> Commit-Queue: Richard Townsend <richard.townsend@arm.com>
> Cr-Commit-Position: refs/heads/master@{#868466}

Bug: 1137393
Bug: 1145581
Bug: 1195009
Change-Id: I8808476cdfb05cccf2d9ee5bcb1674319ddf7c6a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2799936
Commit-Queue: Gabriel Charette <gab@chromium.org>
Owners-Override: Gabriel Charette <gab@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#868517}