[backend]将testdata/下的测例替换为了赛方测试用例，更新了测试脚本

testdata/functional/36_op_priority2.sy

@@ -0,0 +1,9 @@
+//test the priority of add and mul
+int main(){
+    int a, b, c, d;
+    a = 10;
+    b = 4;
+    c = 2;
+    d = 2;
+    return (c + a) * (b - d); 
+}