video: GST_EXPORT -> GST_URI_VIDEO_BAD_API

We need different export decorators for the different libs.
For now no actual change though, just rename before the release,
and add prelude headers to define the new decorator to GST_EXPORT.

gst-libs/gst/video/gstvideoaggregator.h

@@ -29,6 +29,7 @@
 #include <gst/gst.h>
 #include <gst/video/video.h>
 #include <gst/base/gstaggregator.h>
+#include <gst/video/video-bad-prelude.h>
 
 G_BEGIN_DECLS
 
@@ -111,7 +112,7 @@ struct _GstVideoAggregatorClass
   gpointer            _gst_reserved[GST_PADDING_LARGE];
 };
 
-GST_EXPORT
+GST_VIDEO_BAD_API
 GType gst_video_aggregator_get_type       (void);
 
 G_END_DECLS