bug#9782: 24.0.90; move-to-window-line not taking header line into account

[David Engster]

Recipe:

* emacs -Q

* Enter in scratch buffer:

(move-to-window-line (cdr (posn-actual-col-row (posn-at-point))))

and enter an additional newline so this is not the last line in the buffer.

* Move behind last bracket an hit C-x C-e

* Cursor will move to beginning of line, as expected.

* Now do M-: (setq header-line-format "") RET

* Evaluate the above again. You'll see that cursor now will move to the
  beginning of the next line, which is wrong.


This behavior occurs since rev. 106022, which fixed posn-actual-col-row
when a header-line is active, but it seems move-to-window-line now has
to be fixed as well.


Cheers,
David