cvapi: add wrapper for IO surface access

To be used in a future video sink for zero-copy rendering.

sys/applemedia/cvapi.c

@@ -53,6 +53,7 @@ gst_cv_api_obtain (GError ** error)
     SYM_SPEC (CVPixelBufferGetBytesPerRowOfPlane),
     SYM_SPEC (CVPixelBufferGetHeight),
     SYM_SPEC (CVPixelBufferGetHeightOfPlane),
+    SYM_SPEC (CVPixelBufferGetIOSurface),
     SYM_SPEC (CVPixelBufferGetPlaneCount),
     SYM_SPEC (CVPixelBufferGetTypeID),
     SYM_SPEC (CVPixelBufferIsPlanar),

sys/applemedia/cvapi.h

@@ -91,6 +91,8 @@ struct _GstCVApi
   size_t (* CVPixelBufferGetHeight) (CVPixelBufferRef pixelBuffer);
   size_t (* CVPixelBufferGetHeightOfPlane)
       (CVPixelBufferRef pixelBuffer, size_t planeIndex);
+  void * (* CVPixelBufferGetIOSurface)
+      (CVPixelBufferRef pixelBuffer);
   size_t (* CVPixelBufferGetPlaneCount)
       (CVPixelBufferRef pixelBuffer);
   CFTypeID (* CVPixelBufferGetTypeID) (void);