Ticket #3156: fix of panels redraw after toggling hidden files.

(toggle_show_hidden): redraw both panels forced after toggling
hidden files. The bug is appeared when toggling is performed
by mouse clicking on icon in the panel title: current panel
is updated, other one isn't.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Merge branch '3156_toggle_hidden_fix'

* 3156_toggle_hidden_fix:
  Ticket #3156: fix of panels redraw after toggling hidden files.