bug#52461: spontaneous crash with portable dumper

[Eli Zaretskii]

> From: Pip Cet <pipcet@gmail.com>
> Date: Mon, 13 Dec 2021 14:43:55 +0000
> Cc: YAMAMOTO Mitsuharu <mituharu@math.s.chiba-u.ac.jp>, 52461@debbugs.gnu.org
> 
> What we can try is debugging the crashing temacs binary, setting a
> breakpoint to the point where define-charset-internal calls xpalloc
> (in a very strange manner), at about line 1126 in charset.c, and zero
> the memory after the call by executing
>   memset (new_table, 0, new_size * sizeof (new_table[0]))
> in the debugger (I don't use lldb so I'm not sure precisely how to do
> that), then continuing to the memcpy.
> 
> If that fixes things, we should make the obvious change, I think.

Sounds like a plan, thanks.