Add header for foced fork variable. Don't know what it is good for yet. But why not...

include/gds-render/output-renderers/external-renderer-interfaces.h

@@ -73,6 +73,18 @@
  */
 #define EXPORTED_VAR_DECL(VAR) EXPORT_VAR VAR
 
+/**
+ * @brief Define for declaring variables based on a define expansion
+ * @note If you want to declare an exported variable use @ref EXPORTED_VAR_DECL
+ */
+#define VAR_DECL(VAR) VAR
+
+/**
+ * @brief Define for declaring functions based on a define expansion
+ * @note If you want to declare an exported function use @ref EXPORTED_FUNC_DECL
+ */
+#define FUNC_DECL(FUNC) FUNC
+
 /** @} */
 
 #endif /* __EXTERNAL_RENDERER_INTERFACES_H__ */