message: calib3d: fix warning from gcc7
diff: @@ -137,7 +137,7 @@ bool solvePnP( InputArray _opoints, InputArray _ipoints,
  CvMat c_cameraMatrix = cameraMatrix, c_distCoeffs = distCoeffs;
  CvMat c_rvec = rvec, c_tvec = tvec;
  cvFindExtrinsicCameraParams2(&c_objectPoints, &c_imagePoints, &c_cameraMatrix,
  - c_distCoeffs.rows*c_distCoeffs.cols ? &c_distCoeffs : 0,
  + (c_distCoeffs.rows && c_distCoeffs.cols) ? &c_distCoeffs : 0,
  &c_rvec, &c_tvec, useExtrinsicGuess );
  result = true;
  }
  