bug#36597: 27.0.50; rehash hash tables eagerly in pdumper

[Eli Zaretskii]

> From: Pip Cet <pipcet@gmail.com>
> Date: Tue, 11 Aug 2020 15:59:12 +0000
> Cc: Paul Eggert <eggert@cs.ucla.edu>, larsi@gnus.org, 
> 36597-done@debbugs.gnu.org
> 
> I suggest going back to Fmake_vector (h->hash, Qnil), as in the
> attached patch. It's shorter, and it actually compiles.

Yes, I did that, thanks.