bug#61960: 30.0.50; Unexec build reliably crashes during loadup

[Eli Zaretskii]

> From: Konstantin Kharlamov <hi-angel@yandex.ru>
> Date: Sat, 04 Mar 2023 23:05:23 +0300
> 
> So, I kind of reproduced the problem… But it doesn't happen reliably.
> 
> I reconfigured the build with the exact flags, ran `make clean` and `make`, 
> and
> it did fail with a `free(): invalid pointer`.
> 
> However, entering the `src/` dir and running `./temacs --batch -l loadup --
> temacs=bootstrap` doesn't reproduce crash, it finishes successfully.

Remove all the *.elc files and try again.