Clean up ecl SIGCHLD configuration

[vbraun]

Switch from patching ecl to using ecl_set_option(ECL_OPT_TRAP_SIGCHLD, 0).

This ticket was originally a part of #14636.

CC: @SnarkBoojum @jdemeyer @kiwifb

Component: packages: standard

Keywords: ecl signal handling sigchld

Author: Volker Braun, Julien Puydt

Branch/Commit: u/vbraun/ecl_signal_beautification @ 7615258

Reviewer: Jean-Pierre Flori

Issue created by migration from https://trac.sagemath.org/ticket/15441

[vbraun]

Commit: 5ecc849

[vbraun]

Branch: u/vbraun/ecl_signal_beautification

[vbraun]

New commits:

[5ecc849](https://github.com/sagemath/sagetrac-mirror/commit/5ecc849)	test that no SIGCHLD handler was installed
[ecdc36d](https://github.com/sagemath/sagetrac-mirror/commit/ecdc36d)	Use ecl_set_option instead of patching to disable ECL_OPT_TRAP_SIGCHLD

[vbraun]

comment:2

I suspected that this is related to the observed test failure on eno/skynet (#15440) but it is actually not. But its better than what we have so we should ship it.

[kiwifb]

comment:3

Haven't been active in sage for a bit. I needed to back off a little bit. I have to agree that looks much nicer and you added a nice looking doctest.

[SnarkBoojum]

comment:4

The patch to use ecl_set_option looks good, but the doctest patch looks very wrong : it doesn't check that ECL-in-sage doesn't use SIGCHLD, but rather that SIGCHLD isn't used at all!

[vbraun]

comment:5

I don't understand what you are trying to say. It tests both that neither Sage nor ECL set a SIGCHLD handler, i.e. that it remains NULL.

[sagetrac-git]

Changed commit from 5ecc849 to 7615258

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

[7615258](https://github.com/sagemath/sagetrac-mirror/commit/7615258)

clarify test that no SIGCHLD handler is installed

[vbraun]

comment:7

Is this clearer?

[jpflori]

Changed keywords from none to ecl signal handling sigchld

[jpflori]

comment:8

Looks fine to me.
Note I did not run the testsuite, but let's leave that to the patchbot.
And hopefully we'll also update ECL at some point, the sage-on-gentoo folk did that though it was not painless.

[jpflori]

Reviewer: Jean-Pierre Flori