bug#61190: 28.2; ispell personal dictionary location for hunspell engine

[Juri Linkov]

> I looked into the Hunspell's sources, and I think I know why this
> happens.  Hunspell has a peculiar logic when looking for the personal
> dictionary.  The outcome of that peculiar logic is that if Hunspell is
> invoked with "-p PDICT" command-line argument, and PDICT is an
> absolute file name, that file must already exist, or else Hunspell
> will decide it cannot use it.  And Emacs always invokes Hunspell with
> an absolute file name of the personal dictionary.
>
> This is arguably a bug in Hunspell, but a workaround is to create an
> empty file at the location where you want the personal dictionary to
> be, and then restart the speller.

This bug exists even on GNU/Linux, so requires such customization:

  (unless (file-exists-p "~/.hunspell")
    (shell-command "touch ~/.hunspell"))
  (setq ispell-personal-dictionary "~/.hunspell")