bug#68244: hash-table improvements

[Eli Zaretskii]

> Cc: gerd.moellmann@gmail.com, dmitry@gutov.dev, 68244@debbugs.gnu.org,
>  monnier@iro.umontreal.ca, stefankangas@gmail.com
> Date: Tue, 20 Feb 2024 19:12:06 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> 
> Please ask on emacs-devel that the branch be tried on platforms you
> didn't try it, and let's please wait for a few days to give people
> chance to do that and report back.

I've built the branch on this platform and configuration:

  In GNU Emacs 30.0.50 (build 1, i686-pc-mingw32) of 2024-02-21 built on
   ELIZ-PC
  Windowing system distributor 'Microsoft Corp.', version 10.0.22631
  System Description: Microsoft Windows 10 Enterprise (v10.0.2009.22631.3155)

  Configured using:
   'configure -C --prefix=/d/usr --with-wide-int
   --without-native-compilation --enable-checking=yes,glyphs 'CFLAGS=-O0
   -gdwarf-4 -g3''

and it builds cleanly and passes a few tests related to obarrays.