plugins: python renderer: Add fork request to python renderer library, so it wont destory the base application

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

@@ -55,6 +55,11 @@
  */
 #define FUNC_DECL(FUNC) FUNC
 
+/**
+ * @brief Define for declaring exported variables
+ */
+#define VAR_DECL(VAR) VAR
+
 /** @} */
 
 #endif /* __EXTERNAL_RENDERER_INTERFACES_H__ */