android samples: force setVisibility (see #5812)

samples/android/15-puzzle/src/org/opencv/samples/puzzle15/Puzzle15Activity.java

@@ -59,6 +59,7 @@ public class Puzzle15Activity extends Activity implements CvCameraViewListener,
         Log.d(TAG, "Creating and setting view");
         mOpenCvCameraView = (CameraBridgeViewBase) new JavaCameraView(this, -1);
         setContentView(mOpenCvCameraView);
+        mOpenCvCameraView.setVisibility(CameraBridgeViewBase.VISIBLE);
         mOpenCvCameraView.setCvCameraViewListener(this);
         mPuzzle15 = new Puzzle15Processor();
         mPuzzle15.prepareNewGame();