Only define yyscan_t if not already defined by generated code.

controller/controller/controller_load.h

@@ -23,7 +23,10 @@
 #include <stdarg.h>
 
 
-typedef void * yyscan_t;
+#ifndef YY_TYPEDEF_YY_SCANNER_T
+#define YY_TYPEDEF_YY_SCANNER_T
+typedef void* yyscan_t;
+#endif
 
 int controller_load_shell_add(void);