fix angle 0 image rotate error

ppstructure/predict_system.py

@@ -100,6 +100,7 @@ class StructureSystem(object):
                 '180': cv2.ROTATE_180,
                 '270': cv2.ROTATE_90_CLOCKWISE
             }
+            if angle in cv_rotate_code:
                 img = cv2.rotate(img, cv_rotate_code[angle])
             toc = time.time()
             time_dict['image_orientation'] = toc - tic