cc_draw: use const for getFrameThickness()

Origin commit data
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Commit: a5f87f4e00
Author: Thilo Graf <dbt@novatux.de>
Date: 2019-10-27 (Sun, 27 Oct 2019)

src/gui/components/cc_draw.h

@@ -212,7 +212,7 @@ class CCDraw : public COSDFader, public CComponentsSignals, public CCTypes
 		///set frame thickness
 		void setFrameThickness(const int& thickness);
 		///return of frame thickness
-		int getFrameThickness(){return fr_thickness;}
+		int getFrameThickness() const {return fr_thickness;}
 		///set frame color
 		void setColorFrame(fb_pixel_t color){col_frame = color;}