reevaluating org-x11idle-exists-p with new org-clock-x11idle-program-name

[Julien Cubizolles]

I'm using a custom python program to display x11 idle time. I've set
org-clock-x11idle-program-name accordingly but org-x11idle-exists-p is
still nil. I'm guessing it's defvar'ed in org-clock.el before
org-clock-x11idle-program-name is set. Evaluating the defvar of
org-x11idle-exists-p afterwards indeed sets it to t.

I could do (setq org-x11idle-exists-p t) but there must be a better way
to handle the definition of a new org-clock-x11idle-program-name.

-- 
Julien Cubizolles