lisp/org.el: Fix indentation again
* lisp/org.el (org-indent-line): Take care of checking at the
beginning of the line.
Reported-by: Kévin Le Gouguec <kevin.legouguec@gmail.com>
Link: https://orgmode.org/list/878s4wu9oe.fsf@gmail.com/T/#m658a98441dcce099a569ca5b228778aad5d102f3