CComponentsFrmClock: add slot to handle enforced repaint of segments

If clock removed from screen and instance is not destroyed, then we must
ensure repaint of segments after painted background.

This is required if segments are only will paint if
their content was changed and attribut ct_force_text_paint = false.


Origin commit data
------------------
Commit: 81f26a327d
Author: Thilo Graf <dbt@novatux.de>
Date: 2017-01-18 (Wed, 18 Jan 2017)

src/gui/components/cc_frm_clock.h

@@ -52,7 +52,10 @@ class CComponentsFrmClock : public CComponentsForm, public CCTextScreen
 
 	protected:
 		///slot for timer event, reserved for ShowTime()
-		sigc::slot0<void> cl_sl;
+		sigc::slot0<void> cl_sl_show;
+
+		///slot for background paint event, reserved for initCCLockItems()
+		sigc::slot0<void> cl_sl_repaint;
 
 		///refresh interval in seconds
 		int cl_interval;
@@ -90,6 +93,8 @@ class CComponentsFrmClock : public CComponentsForm, public CCTextScreen
 		void toggleFormat();
 		///init internal font
 		void initClockFont(int dx, int dy);
+		///force repaint of all segments
+		void forceSegemnentsPaint(bool force);
 
 	public: