请求队列相关函数修改

修改了部分函数的定义

test/rail_test.cpp

@@ -41,7 +41,7 @@ TEST(rail, CreateRails)
 TEST(rail, FindNode)
 {
     rail_node_t *head = CreateRails(10, 10);
-    rail_node_t *p = nullptr;
+    rail_node_t *p;
 
     p = FindNode(head, 3);
     EXPECT_EQ(p->id, 3);
@@ -50,6 +50,12 @@ TEST(rail, FindNode)
     EXPECT_EQ(p->id, 9);
 }
 
+TEST(rail, FreeRails)
+{
+    rail_node_t *head = CreateRails(10, 10);
+    FreeRails(head);
+}
+