Add MacOS X support for client: handle cl-readline

[ryukinix]

GNU Readline is not commonly available on Mac OS. How we can handle tihs?

[fu7mu4]

In my macOS, it seems to be worked well

• Intel macOS
• Venture (13.3.1)
• gnu readline installed by using homebrew
  • brew install readline https://formulae.brew.sh/formula/readline

[fu7mu4]

see https://github.com/vindarel/cl-readline

# Installation

Via Quicklisp (recommended):

(ql:quickload "cl-readline")

If you are using Homebrew on a Mac, please note that GNU Readline has keg-only formula, which means you may need to link the library yourself:

$ brew link readline --force