For GST_EXPORT define and also things like GST_DISABLE_REGISTRY.
Hopefully fixes the following build failure on cerbero-cross-mingw32:
helpers/gst-plugin-scanner.c:50: undefined reference to `_imp___gst_disable_registry_cache'
#include <stdlib.h>
#include <string.h>
#include <stdlib.h>
#include <string.h>
+/* Needed for GST_EXPORT */
+#include "gstconfig.h"
+
/* Needed for GstRegistry * */
#include "gstregistry.h"
#include "gststructure.h"
/* Needed for GstRegistry * */
#include "gstregistry.h"
#include "gststructure.h"