bug#46881: 28.0.50; pdumper dumping causes way too many syscalls

[Pip Cet]

> My quick test on macOS by doing:
>
> rm src/*.pdmp
> time make
>
> sees it going from ~26s without patch to ~10s with patch, so a
> considerable improvement.

Thanks for testing!

> > > Patch will be attached once this has a bug number.
> >
> > And here's the patch. Testing would be very appreciated.
>
> It appears to work fine here, but I don't know if there's anything
> specific to test other than just running Emacs.

I suspect there may be problems on systems with very little memory. Do
you have an easy way to determine maximum resident size (on Debian
GNU/Linux, /bin/time works)? It would be interesting to see if that's
actually different.

Thanks again!
Pip