Change default value of org-clock-x11-idle-program-name (was: org-x11idle-exists-p with emacs --daemon)

[Ihor Radchenko]

Max Nikulin <manikulin@gmail.com> writes:

> x11idle as `org-clock-x11idle-program-name' default is questionable as 
> well. Debian, Arch, Gentoo have xprintidle packages and this tool have 
> some additional code.

AFAIU, x11idle was a very old hard-coded default. Later, this variable
had been introduced without changing the default.

What we can do is check if xprintidle executable is available and use
it. Otherwise, fall back to x11idle to retain backwards compatibility on
systems that do no have xprintidle installed.

WDYT?

-- 
Ihor Radchenko // yantar92,
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