[Toybox] [PATCH] Fix xsignal_all_killers().

[Rob Landley]

On 8/30/21 10:56 AM, enh via Toybox wrote:
> Found in github CI by the existing patch tests:
> ```
> patch: xsignal 0: Invalid argument
> ```

Yeah, I bumped into that right after I pushed your commit (it broke the mkroot
linux kernel build) but got distracted trying to integrate
scripts/record-commands into mkroot.sh instead of immediately fixing it.

> When I grepped for places that would be affected by my `kill -0` change,
> I grepped toys/, not lib/. (And I only ran the tests for the toys I
> touched, not all the tests, and CI was already broken so we didn't
> notice the new breakage until the old breakage was fixed :-( )

Your commit changed list_signals() to start from 1 but didn't do the same for
xsignal_all_killers(). One character fix. Pushed now, sorry for the delay. (I've
been mostly AFK this week.)

Rob