Update test_fld.cpp

Author: sturkmen72

modules/ximgproc/test/test_fld.cpp

@@ -286,6 +286,7 @@ TEST_F(ximgproc_ED, ManySmallCircles)
     vector<Vec6d> ellipses;
     detector->detectEdges(test_image);
     detector->detectEllipses(ellipses);
+    detector->detectLines(lines);
 
     size_t segments_size = 6458;
     size_t lines_size = 6264;