bug#33460: 24.4; Eshell histfile symlinks not followed

[Eli Zaretskii]

> From: Philip Hudson <phil.hudson@iname.com>
> Date: Wed, 21 Nov 2018 23:09:16 +0000
> 
> If the file named by the value of option `eshell-history-file-name' is
> a symbolic link, then it will be replaced and overwritten instead. It
> should be dereferenced (followed) first, and its target file should be
> replaced and overwritten.
> 
> The attached patch uses function `file-truename' to fix this. The
> patch was made using source cloned from git savannah HEAD today, which
> I think is version 26.1.90, based on ChangeLog.3 in the cloned repo.

Thanks, pushed to the master branch, to appear in Emacs 27.1.

Please in the future provide a ChangeLog-style commit log entry for
your changes; see CONTRIBUTE for the details.

Also, user-visible behavior changes need to be called out in NEWS, and
if necessary also in the relevant Texinfo manual(s).