modified lib GPC for header only

worked on 3d traytracing

geo/volume/BoundingVolumeAABB.h

@@ -20,7 +20,7 @@ public:
 	/** empty ctor */
 	BoundingVolumeAABB() : p1(MAX,MAX,MAX), p2(MIN,MIN,MIN) {;}
 
-	float getVolumeSize() const override {
+	float getVolumeSize() const  {
 		return (p2.x-p1.x) * (p2.y-p1.y) * (p2.z-p1.z);
 	}