修复了结构体定义错误

src/query.c

@@ -3,6 +3,6 @@
 //
 #include "query.h"
 
-up_bus_t* up_queries;
-down_bus_t *down_queries;
+up_bus_t* up_queries = NULL;
+down_bus_t *down_queries = NULL;
 

src/rail.c

@@ -1,6 +1,6 @@
 #include "rail.h"
 
-rail_node_t *rails;
+rail_node_t *rails = NULL;
 
 int add(int a, int b)
 {