[ruby-cvs:78254] cef9ebfbd3 (master): Suppress `stty` error on Apple Terminal

Nobuyoshi Nakada	2019-11-13 15:28:12 +0900 (Wed, 13 Nov 2019)

  New Revision: cef9ebfbd3

  https://github.com/ruby/ruby/commit/cef9ebfbd3

  Log:
    Suppress `stty` error on Apple Terminal
    
    `stty` called in `Reline::ANSI.deprep` command shows the following
    error message on macOS Apple Terminal, with some settings.
    
    ```
    $ LANG=C irb
    irb(main):001:0>
    stty: 'standard input': unable to perform all requested operations
    stty: 'standard input': unable to perform all requested operations
    ```

  Modified files:
    lib/reline/ansi.rb