Description:
------------
When running `php -a` it is supposed to either print "Interactive
shell" or "Interactive mode enabled" depending on readline/libedit
support. However, this is determined during compile time[1], and
as such can't work reliably, since we can't know whether a shared
extension will actually be available or not.

Linux:
    $ ./configure --disable-all --with-readline=shared
    $ make
    $ sapi/cli/php -d extension=modules/readline.so -a
    Interactive mode enabled

    php >

Windows:
    $ configure --disable-all --enable-cli
    $ nmake
    $ x64\Release_TS\php -a
    Interactive shell

See also bug #70543.

[1] <https://github.com/php/php-src/blob/ab8094c/sapi/cli/php_cli.c#L918-L922>