message: Replaced macro with built-in OpenCV export
diff: #import <ImageIO/ImageIO.h>
  #include "opencv2/core.hpp"
  -#define OPENCV_OBJC_EXPORT __attribute__((visibility("default")))
  -
  //! @addtogroup videoio_ios
  //! @{
  @class CvAbstractCamera;
  -OPENCV_OBJC_EXPORT @interface CvAbstractCamera : NSObject
  +CV_EXPORTS @interface CvAbstractCamera : NSObject
  {
  UIDeviceOrientation currentDeviceOrientation;
  @@ -89,7 +87,7 @@ OPENCV_OBJC_EXPORT @interface CvAbstractCamera : NSObject
  @class CvVideoCamera;
  -OPENCV_OBJC_EXPORT @protocol CvVideoCameraDelegate <NSObject>
  +CV_EXPORTS @protocol CvVideoCameraDelegate <NSObject>
  #ifdef __cplusplus
  // delegate method for processing image frames
  @@ -98,7 +96,7 @@ OPENCV_OBJC_EXPORT @protocol CvVideoCameraDelegate <NSObject>
  @end
  -OPENCV_OBJC_EXPORT @interface CvVideoCamera : CvAbstractCamera<AVCaptureVideoDataOutputSampleBufferDelegate>
  +CV_EXPORTS @interface CvVideoCamera : CvAbstractCamera<AVCaptureVideoDataOutputSampleBufferDelegate>
  {
  AVCaptureVideoDataOutput *videoDataOutput;
  @@ -131,14 +129,14 @@ OPENCV_OBJC_EXPORT @interface CvVideoCamera : CvAbstractCamera<AVCaptureVideoDat
  @class CvPhotoCamera;
  -OPENCV_OBJC_EXPORT @protocol CvPhotoCameraDelegate <NSObject>
  +CV_EXPORTS @protocol CvPhotoCameraDelegate <NSObject>
  - (void)photoCamera:(CvPhotoCamera*)photoCamera capturedImage:(UIImage *)image;
  - (void)photoCameraCancel:(CvPhotoCamera*)photoCamera;
  @end
  -OPENCV_OBJC_EXPORT @interface CvPhotoCamera : CvAbstractCamera
  +CV_EXPORTS @interface CvPhotoCamera : CvAbstractCamera
  {
  AVCaptureStillImageOutput *stillImageOutput;
  }
  