bug#73656: 30.0.91; icomplete-vertical has no matches for M-x man RET chdir

[Stefan Monnier via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

> +                         (if (eq system-type 'berkeley-unix) "-l")

Maybe a more robust approach would be something like

    (defvar man--apropos-args (...))

where (...) is a piece of code which actually runs `man` with `-k` and
with or without `-l` to try and determine which kind of `man` we're
dealing with, but without making assumptions about which kind of `man`
is installed on which kind of OS.

Then we can use this new `man--apropos-args` var when running
`process-file`.

Oh, and `process-file` makes this worse because it may end up spawning
a process on a remote systems, so the local OS and local `man` may not
have anything to do with the remote OS and remote `man`.


        Stefan